I 

EXAMINATION  OF  WATER. 


LEFFMANN  AND  BEAM. 


PROGRESSIVE  EXERCISES 

IN 

PRACTICAL  CHEMISTRY. 

BY 

HENRY  LEFFMANN  AND  WILLIAM  BEAM. 

i2mo.     Illustrated.    $1.00. 


A  COMPEND  OF  CHEMISTRY, 

INORGANIC  AND  ORGANIC. 

INCLUDING 

URINARY      ANALYSIS. 

BY 

HENRY  LEFFMANN. 

ESPECIALLY  ADAPTED  TO  STUDENTS  IN  MEDICINE 
AND  DENTISTRY. 

Third  Edition.     Revised. 
Price  $1.00.     Interleaved,  for  taking  Notes,  $1.25. 


P.   BLAKISTON,   SON   &  CO. 


EXAMINATION  OF  WATER 


FOR 


SANITARY    AND    TECHNICAL   PURPOSES. 


HENRY  LEFFMANN,  M.  D.,  PH.D., 

IV 

PROFESSOR    OF  CHEMISTRY  IN  THE  WOMAN'S   MEDICAL  COLLEGE   OF  PENNSYLVANIA, 

IN   THE    PENNSYLVANIA    COLLEGE    OF    DENTAL   SURGERY  AND    IN   THE 

WAGNER  FREE  INSTITUTE  OF  SCIENCE  ;    PATHOLOGICAL 

CHEMIST   TO   THE   JEFFERSON     MEDICAL 

COLLEGE      HOSPITAL. 


WILLIAM    BEAM,  M.  A., 

DEMONSTRATOR    OF    CHEMISTRY   IN  THE    PENNSYLVANIA    COLLEGE    OF    DENTAL 

SURGERY  ;   ASSOCIATE  OF  THE  SOCIETY  OF  PUBLIC  ANALYSTS 

OF   GREAT   BRITAIN;     FORMERLY    CHIEF 

CHEMIST  B.  &  O.  R.  R. 


SECOND  EDITION,  REVISED  AND  ENLARGED,  W{7  H 


PHILADELPHIA : 

P.   BLAKISTON,   SON    &    CO., 

IOI2    WALNUT    STREET. 
1891. 


WVBKSIT7 


Copyright,  1890,  by  P.  BLAKISTON,  SON  &  Co. 


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PRESS    OF    WM.    F.    FELL    &    CO. 

1220-24    SANSOM    STREET. 

PHILADELPHIA. 


PREFACE. 


IN  the  period  that  has  elapsed  since  the  publication  of 
the  first  edition  of  this  work,  many  processes  for  water 
analysis  have  been  proposed,  and  we  have  included  in  the 
present  revision  such  of  these  as  seem  to  us  of  substantial 
value.  In  particular  we  may  mention  the  methods  recom- 
mended by  the  Chemical  Section  of  the  American  Associa- 
tion for  the  Advancement  of  Science,  and  the  application 
of  the  Kjeldahl  process  to  the  determination  of  the  organic 
nitrogen.  The  adoption  of  the  former  methods  will  serve 
to  secure  uniformity  in  analytical  data,  while  it  is  to  be 
hoped  that  chemists  generally  will  investigate  and  report 
on  the  latter,  in  order  that  a  basis  for  the  interpretation 
of  results  may  be  obtained. 

No  material  change  has  been  made  in  the  description  of 
the  general  Quantitative  Analysis,  in  which  we  have  followed 
to  a  large  extent  the  methods  indicated  by  Fresenius, 
selecting  those  best  adapted  to  technical  purposes. 

We  have  extended  considerably  the  section  on  the 
Biological  Examinations,  although  we  have  seen  no  reason 
to  change  the  opinions  expressed  in  the  former  edition  as 
to  the  value  of  these  results.  It  would  be  impossible  to 
overestimate  the  importance  of  bacteriology,  in  etiology, 
pathology  and  general  biology,  but  until  pathogenic  mi- 
crobes are  more  clearly  indicated  and  described,  the 

v 


VI  PREFACE. 

methods  will  be  of  little  use  in  dealing  with  the  problem 
of  the  determination  of  the  sanitary  and  technical  value  of 
water  supplies. 

In  the  chapter  on  the  Purification  of  Water  we  have 
described  in  some  detail  a  few  of  the  important  systems, 
especially  the  Anderson  iron  process,  the  efficiency  of 
which  we  have  had  ample  opportunity  to  observe  by 
experiments  on  a  comparatively  large  scale,  extending 
over  several  months. 

The  favorable  reception  accorded  to  the  first  edition, 
both  by  journals  of  acknowledged  authority,  and  by 
chemists  of  extended  experience  in  this  department,  has 
indicated  that  the  work  is  not  without  usefulness  in  the 
field  to  which  it  is  devoted.  H.  L. 

W.  B. 
f/j  Walnut  St. 

December,  i8go. 


CONTENTS. 


HISTORY  OF  NATURAL  WATERS. 

Classification  —  Rain  Water  —  Surface  Water— Subsoil 
Water— Deep  Water, 9-15 

ANALYTICAL  OPERATIONS. 
Sanitary  Examinations : — 

Collection  and  Preliminary  Examination — Total  Solids — 
Chlorine — Nitrogen  in  Ammonium  Compounds  and 
in  Organic  Matter — Nitrogen  as  Nitrates — Nitrogen  as 
Nitrites  —  Oxygen-consuming  Power  —  Phosphates — 

Dissolved  Oxygen — Poisonous  Metals, 16— 53 

Technical  Examinations  : — 

General  Quantitative  Analysis — Spectroscopic  Analysis — 
Specific  Gravity, 53-^9 

INTERPRETATION  OF  RESULTS. 

Statement  of  Analysis, 70-82 

Sanitary  Applications — Action  of  Water  on  Lead,    ....         83 

BIOLOGICAL  EXAMINATIONS, 85-96 

PURIFICATION  OF  DRINKING  WATER, 98-107 

IDENTIFICATION  OF  SOURCE  OF  WATER, 107-110 

TECHNICAL  APPLICATIONS. 

Boiler  Waters — Purification  of  Boiler  Waters — Sewage 
Effluents Iii-n8 

ANALYTICAL  DATA. 

Factors  for  Calculation — Conversion  Table — Oxygen  Dis- 
solved in  Water — Rain  and  Subsoil  Waters — Schuylkill 
Water — Artesian  Waters — City  Supplies,   .    .    .    .119-125 
vii 


EXAMINATION  OF  WATER. 


HISTORY   OF   NATURAL  WATERS. 

Pure  water  is  an  artificial  product  of  the  laboratory. 
Natural  waters  always  contain  foreign  matters  in  solution 
and  suspension,  varying  from  mere  traces  to  very  large 
proportions.  The  properties,  effects  and  uses  of  water  are 
considerably  modified  by  these  ingredients,  and  the  object 
of  analysis  is  to  ascertain  their  character  and  amount. 
Since  these  are  largely  dependent  on  the  history  of  the 
water,  a  classification  based  on  this  will  be  convenient. 
We  may  distinguish  four  classes  of  natural  waters  : — 

Rain  Water. — Water  precipitated  from  the  atmosphere 
under  any  conditions,  and  therefore  including  dew,  frost, 
snow  and  hail. 

Surface  Water. — All  collections  of  water  in  free  contact 
with  the  atmosphere,  as  in  streams,  seas,  lakes,  or  ponds. 

Subsoil  or  Ground  Water. — Water  not  in  free  contact 
with  the  atmosphere,  percolating  or  flowing  through  soil  or 
rock  at  moderate  distance  below  the  surface,  and  derived 
in  large  part  from  the  rain  or  surface  water  of  the  district. 

Deep  or  Artesian  Water. — Water  accumulated  at  con- 
siderable depth  below  the  surface,  from  which  the  subsoil 
water  of  the  district  has  been  excluded  by  difficultly  per- 
meable strata. 

Rain  Water,  when  gathered  in  the  open  country  and 
B  9 


10  HISTORY    OF    NATURAL   WATERS. 

in  the  latter  period  of  a  long  rain  or  snow,  is  the  purest 
form  of  natural  water.  When  collected  directly,  it  con- 
tains but  little  solid  matter,  this  consisting  principally  of 
ammonium  compounds  and  particles  of  organic  matter, 
living  and  dead,  gathered  from  the  atmosphere.  In  dis- 
tricts near  the  sea  an  appreciable  amount  of  chlorides  will 
be  present.  It  is  obvious  that  a  prolonged  rain  will  wash 
out  the  air,  but  since  storms  are  usually  attended  by  wind, 
fresh  portions  of  air  are  continually  flowing  in,  and  thus  the 
water  never  becomes  perfectly  pure.  Rain  water  collected 
in  inhabited  districts  is  usually  quite  impure. 

Surface  Water. — Rain  water  in  part  flows  off  on  the 
surface,  and  gains  in  the  proportion  of  suspended  and  dis- 
solved matters,  the  former  being  found  in  large  amount 
when  the  rainfall  is  profuse.  The  wearing  action  of  water 
is  dependent  on  the  amount  and  character  of  these  sus- 
pended materials.  From  the  higher  levels  of  a  watershed, 
the  streams,  more  or  less  in  the  form  of  torrents,  gather  into 
larger  currents,  and  reaching  lower  levels  become  slower 
in  movement,  and  deposit  much  of  the  suspended  matter. 
By  admixture  of  the  waters  from  widely  separated  districts 
the  character  and  amount  of  the  dissolved  matters  are  much 
modified.  An  action  of  this  kind  is  seen  in  the  watershed 
of  the  Schuylkill  River.  This  stream  rises  in  the  anthracite- 
coal  region  of  Pennsylvania,  and  receiving  much  refuse 
mine-water  becomes  impregnated  with  iron  salts  and  free 
mineral  acid,  being  then  quite  unsuitable  for  drinking  or 
manufacturing  purposes.  In  its  course  of  about  one  hundred 
miles,  it  passes  over  an  extensive  limestone  district,  and 
receives  several  large  streams  highly  charged  with  calcium 
carbonate.  The  result  is  a  neutralization  of  the  acid,  and  a 
precipitation  of  the  iron  and  much  of  the  calcium.  The  river 


SUBSOIL   WATER.  II 

becomes  purer,  and  at  its  junction  with  the  Delaware  River 
at  Philadelphia,  it  contains  neither  free  sulphuric  nor  hydro- 
chloric acid,  only  traces  of  iron,  and  but  a  small  amount 
of  calcium  sulphate.  In  this  manner  there  is  produced  a 
soft  water,  superior  to  that  of  the  river  near  its  source,  or 
to  the  hard  waters  of  the  middle  Schuylkill  region. 

It  is  obviously  impossible  to  establish  close  standards  of 
composition  for  surface  waters.  In  the  case  of  rain  water, 
falling  on  the  surface  of  undisturbed,  unpopulated  territory, 
the  amount  of  solids  dissolved  will  be  small,  and  will  consist 
principally  of  carbonates  and  sulphates.  The  water  of 
lakes  and  rivers  is,  however,  in  part  derived  from  springs, 
which  may  proceed  from  great  depths,  and  thus  introduce 
substances  not  easily  soluble  in  surface  water,  nor  derivable 
from  the  soil  of  the  district. 

The  exposure  to  light  and  air  which  surface  water  under- 
goes, results  in  the  absorption  of  oxygen  and  loss  of  carbonic 
acid,  together  with  the  oxidation  of  the  organic  matter. 
The  diminution  of  the  rapidity  of  the  current  permits 
the  deposition  of  the  suspended  matters,  and  this  occurs 
especially  as  the  river  approaches  the  sea,  not  only  from 
the  retarding  influence  of  the  tidal  wave,  but  from  the  pre- 
cipitating action  of  the  salt  water.  The  investigations  of 
Carl  Barus,  published  in  Bulletin  No.  36,  U.  S.  Geological 
Survey,  have  shown  the  decided  influence  of  sodium 
chloride  in  accelerating  the  subsidence  of  fine  particles. 

Subsoil  Water. — Water  which  penetrates  the  soil, 
passes  to  various  depths,  acccording  to  the  porosity  and 
arrangement  of  the  strata.  As  a  rule,  it  descends  until  it 
reaches  but  slightly  pervious  formations,  upon  the  level  of 
which  it  accumulates.  In  the  upper  layer  of  soil  it  dissolves 
mineral  and  organic  ingredients,  and  becomes  impregnated 


12  HISTORY   OF   NATURAL   WATERS. 

with  microorganisms,  through  the  agency  of  which  the 
organic  matter  undergoes  important  transformations.  The 
water  constantly  accumulating,  gradually  flows  along  the 
incline  of  the  impervious  stratum,  or  through  its  fissures, 
and  may  either  pass  downward  or  emerge  in  the  form  of  a 
spring. 

The  proportion  of  water  which  may  be  held  by  any  rock 
or  soil  is  often  much  larger  than  would  be  at  first  supposed. 
T.  Sterry  Hunt  states  that  a  square  mile  of  sandstone  100 
feet  thick  will  contain  water  sufficient  to  sustain  a  flow  of  a 
cubic  foot  a  minute  for  more  than  thirteen  years. 

Much  difference  is  observed  in  the  composition  of  sub- 
soil waters,  but  as  a  general  rule  they  contain  but  a  limited 
amount  of  mineral  substances,  and  a  very  small  proportion  of 
organic  matter.  In  populated  districts,  however,  a  marked 
change  is  produced  through  admixture  with  water  contain- 
ing animal  and  vegetable  products  in  various  stages  of  decom- 
position. It  is  especially  the  organic  matter  containing 
nitrogen  that  is  of  importance.  To  this  class  belong  all 
those  compounds  forming  tissues  that  are  intimately 
associated  with  vital  action ;  also  many  characteristic 
excretory  products.  These  bodies  are  mostly  unstable, 
and  as  soon  as  their  vitality  ceases  begin  to  decom- 
pose, partly  by  oxidation,  partly  by  splitting  up  into 
simpler  forms ;  these  changes  being  in  most  cases  brought 
about  by  microorganisms.  Among  the  products  noticed  in 
the  early  stages  of  such  decay,  are  substances  which  possess 
close  analogies  to  the  organic  bases  or  alkaloids,  but  more 
susceptible  of  decomposition.  They  are  generally  present 
in  minute  amount,  but  are  not  infrequently  very  active  in 
their  physiological  effect.  From  the  most  recent  researches  it 
seems  probable  that  the  pathogenic  power  of  many  micro- 


SUBSOIL  WATER.  13 

organisms  rests  not  upon  any  mechanical  or  other  action  of 
the  germs  themselves,  but  upon  the  alkaloidal  principles 
which  they  produce  and  excrete.  As  a  group  these  bodies 
are  known  as  the  "  ptomaines."  Nitrogen  is  an  invariable 
ingredient.  The  ultimate  results  of  the  processes  of  de- 
composition depend  largely  on  circumstances.  When 
organic  matters  containing  nitrogen  are  subjected  to  the 
action  of  oxidizing  agents,  such  as  alkaline  potassium  per- 
manganate or  chromic  acid,  some  of  the  nitrogen  is  con- 
verted into  ammonia.  A  similar  result  occurs  in  all  waters, 
but  a  considerable  portion  of  the  organic  matter  may  also 
suffer  further  oxidation  and  in  association  with  the  mineral 
substances  present  form  nitrites  and  nitrates,  especially  the 
latter.  This  conversion  is  called  "nitrification."  The 
conditions  under  which  it  occurs  have  been  carefully  studied 
by  Warrington,  Munro  and  others. 

Nitrification  takes  place  under  the  influence  of  microbes, 
the  habitat  of  which  does  not  extend  more  than  a  few  yards 
below  the  surface  of  the  soil.  Percy  and  Grace  Frankland 
have  isolated  and  described  a  bacillus  with  active  nitrifying 
powers.  It  is  a  very  short,  almost  spherical  form,  which 
grows  in  ammoniacal  culture-fluids  and  in  meat-broth,  but 
does  not  grow  in  the  usual  gelatin-peptone  mixture,  except 
when  previously  cultivated  in  meat-broth.  The  nitri- 
fying action  is  probably  exerted  only  upon  the  ammonium 
which  is  formed  from  the  organic  matter.  The  presence 
of  some  substance  capable  of  neutralizing  acids  is  necessary 
to  continuous  action.  Calcium  and  magnesium  carbon- 
ates fulfill  this  function.  Nitrates  are  the  final  result  of 
this  action ;  nitrites  are  present  at  any  given  time  only  in 
small  quantity.  Denitrification,  that  is,  the  reduction 
of  nitrates  and  nitrites  to  ammonium,  takes  place  under 


14  HISTORY    OF   NATURAL   WATERS. 

the  influence  of  microbes,  and  is  especially  apt  to  occur 
when  considerable  quantities  of  decomposing  organic  mat- 
ter are  introduced.  Percy  and  Grace  Frankland  have 
described  several  species  of  bacilli  which  have  active  de- 
nitrifying powers.  Among  these  are  Bacillus  liquidus,  B. 
vermicularis  and  B.  ramosus.  A  partial  reduction  some- 
times occurs,  and  a  notable  proportion  of  nitrites  is  found, 
but  in  the  presence  of  actively  decomposing  organic  matter, 
such  as  that  in  sewage,  a  complete  reduction,  even  to  the 
liberation  of  nitrogen,  may  occur. 

Deep  Water. — Water  which  penetrates  the  fissures  of 
the  fundamental  rock  formations  may  pass  to  great  depths, 
and  by  following  the  lines  of  the  lowest  and  least  perme- 
able strata  may  be  transported  to  points  far  removed  from 
those  at  which  it  was  originally  collected.  The  chemical 
changes  thus  induced  include  most  of  those  which  take 
place  at  higher  points,  but  the  increase  of  pressure  and 
temperature  confers  increased  power.  Carbonic  acid  will 
accumulate  under  conditions  favorable  to  the  solution  of 
calcium,  magnesium  and  iron  carbonates,  and  iron  and 
manganese  oxides  may  be  converted  into  carbonates  and 
then  dissolved.  Sulphates  are  reduced  to  sulphides,  and 
these  subsequently,  by  the  action  of  carbonic  acid,  yield 
hydrogen  sulphide.  Organic  matter,  living  and  dead, 
plays  an  important  part,  determining  the  reduction  of  ferric 
compounds  to  ferrous,  and  of  the  sulphates  to  sulphides, 
and  is  itself  converted  ultimately  into  ammonium  com- 
pounds, notable  quantities  of  which  are  often  found  in  deep 
waters.  Further,  it  is  found  that  nitrates  and  nitrites  are 
present  only  in  small  amount,  except  from  certain  strata 
rich  in  organic  matter.  In  some  cases  the  water  acquires 
very  high  temperature,  and  dissociation  of  rocks  occurs, 


DEEP    WATER.  15 

with  solution  of  considerable  amounts  of  silicic  acid,  which 
is  ordinarily  but  sparingly  soluble  in  water. 

Masses  of  water  thus  accumulated  under  heat  and  pres- 
sure may  find  their  way  to  the  surface  either  through  natural 
fissures,  or  be  reached  by  borings.  The  mineral  springs, 
highly  charged  with  solid  matters,  and  the  artesian  waters, 
are  obtained  in  this  way. 

While  no  absolute  unchangeable  line  can  be  drawn  be- 
tween deep  and  subsoil  waters,  yet  it  will  in  most  cases  be 
found  that  the  deep  water  of  a  given  district,  whether 
obtained  through  natural  or  artificial  channels,  will  be 
decidedly  different  in  composition  from  the  subsoil  or  sur- 
face water  of  the  same,  and  that  the  rocks  passed  through 
in  such  cases  will  be  characterized  by  one  or  more  strata, 
difficultly  permeable  to  water,  and  therefore  preventing 
direct  communication.  The  characteristic  differences  be- 
tween surface,  subsoil,  and  deep  waters  are  clearly  indi- 
cated in  the  table  of  analyses  made  by  us  as  given  in  the 
Appendix. 

The  fact  that  mere  depth  is  not  the  essential  difference 
between  the  two  classes  of  waters  is  shown  by  comparison 
between  the  composition  of  the  water  from  the  well  at 
Barren  Hill,  on  the  northern  border  of  Philadelphia  county, 
and  the  deep  well  at  Locust  Point,  Baltimore.  The  former 
is  a  dug  well,  130  feet  deep ;  the  latter  is  an  artesian  bor- 
ing of  128  feet,  which  in  its  descent  passes  through  four 
feet  of  solid  rock.  The  deeper  well  is  evidently  supplied 
by  subsoil  water.  The  artesian  well,  though  located  100 
yards  from  a  brackish  sewage-laden  estuary,  evidently  de- 
rives no  water  from  it. 


ANALYTICAL  OPERATIONS. 

SANITARY  EXAMINATIONS. 

COLLECTION    AND    PRELIMINARY    EXAMINATION 
OF  SAMPLES. 

FlG-  x-  Great  care  must  be  taken  in  collect- 

ing water  samples,  in  order  to  secure  a 
fair  representation  of  the  supply  and  to 
avoid  introduction  of  foreign  matters. 
The  five-pint  green  glass  stoppered  bot- 
tles used  for  holding  acids  are  suitable 
for  containing  the  samples.  The  con- 
tents of  one  such  bottle  will  suffice  for 
most  sanitary  or  technical  examinations. 
Fig.  i  shows  a  bottle  encased  in  wood, 
and  known  under  the  name  of  the 
11  Penn  Demijohn,"  which  we  have 
found  very  convenient  for  transporta- 
tion. It  is  provided  with  a  hinged  lid  which  can  be 
securely  fastened  by  a  padlock.  The  green  glass  stop- 
pered bottles  may  also  be  fitted  to  such  an  arrangement. 
Stone  jugs,  casks  or  metal  vessels  must  not  be  employed. 
The  bottles  used  must  be  thoroughly  rinsed  several  times 
with  the  water  to  be  examined,  filled  and  the  stopper  tied 
down,  or  fastened  by  stretching  a  rubber  'finger-cot  over 
the  stopper  and  lip.  If  corks  are  used,  they  should  be  new 
and  thoroughly  rinsed.  No  wax,  putty,  plaster  or  similar 
material  should  be  used. 

16 


SANITARY    EXAMINATIONS.  I  7 

In  taking  samples  from  lakes,  slow  streams  or  reservoirs, 
it  is  necessary  to  submerge  the  bottle  so  as  to  avoid  collect- 
ing any  water  that  has  been  in  immediate  contact  with  the 
air. 

In  the  examination  of  public  water  supplies,  the  sample 
should  be  drawn  from  a  hydrant  in  direct  connection 
with  the  main,  and  not  from  a  cistern,  storage  tank  or  dead 
end  of  a  pipe.  In  the  case  of  pump-wells,  a  few  gallons  of 
water  should  be  pumped  out  before  taking  the  sample,  in 
order  to  remove  that  which  has  been  standing  in  the  pipe. 

In  all  cases  care  should  be  taken  to  fill  the  vessel  with  as 
little  agitation  with  air  as  possible. 

It  is  important  that  with  each  sample  a  record  be  made 
of  those  surroundings  and  conditions  which  might  influ- 
ence the  character  of  the  water,  particularly  in  reference  to 
sources  of  pollution,  such  as  proximity  to  cesspools,  sewers 
or  manufacturing  establishments.  The  character  and  con- 
dition of  the  different  strata  of  the  locality  should  be  noted 
if  possible. 

Determinations  of  nitrogen  existing  as  ammonium  com- 
pounds, and  as  organic  matter,  and  of  oxygen-consuming 
power,  should  be  made  upon  the  sample  in  the  original 
condition,  whether  turbid  or  clear,  but  all  other  estimations 
should  be  made  upon  the  clear  liquid.  Turbid  waters  may 
be  clarified  by  standing  or  by  filtration  ;  for  the  latter  pur- 
pose Schleicher  &  Schiill's  extra  heavy  No.  598  paper  is 
the  best.  In  many  cases  the  suspended  matter  cannot  be 
entirely  removed  by  filtration,  and  subsidence  must  be  re- 
sorted to.  The  use  of  a  small  quantity  of  alum,  as  described 
in  the  section  on  the  purification  of  water,  will  sometimes 
be  applicable  as  a  rapid  means  of  clarifying  water  samples. 
For  [the  quantitative  determination,  the  sediment  from  a 


1 8  ANALYTICAL   OPERATIONS. 

known  volume  of  the  water  is  collected  on  a  tared  filter, 
dried  at  112°  F.,  and  weighed. 

The  water  from  newly-dug  wells  is  generally  turbid  and 
the  determinations  are  best  made  after  filtration,  but  the 
results  will  be  unsatisfactory,  showing  a  higher  proportion 
of  organic  matter  than  will  be  found  when  the  supply  be- 
comes clear. 

The  following  methods  of  determining  color  and  odor 
have  been  adopted  by  the  Society  of  Public  Analysts  of 
Great  Britain  : — 

Color. — A  colorless  glass  tube,  2  feet  long  and  2  inches 
in  diameter,  is  closed  at  each  end  with  a  disc  of  colorless 
glass.  An  opening  for  filling  and  emptying  the  tube  should 
be  made  at  one  end,  either  by  cutting  a  small  segment  off 
the  glass  disc,  or  cutting  out  a  small  segmental  section  of 
the  tube  itself  before  the  disc  is  cemented  on.  A  good 
cement  for  such  purposes  is  the  following  : — 

Caoutchouc, 2  parts. 

Mastic, 6     " 

Chloroform, 100     " 

The  ingredients  are  mixed  and  allowed  to  stand  for  a 
few  days.  The  cement  should  be  used  as  soon  as  solution 
is  effected,  as  it  becomes  viscid  on  standing. 

The  tube  must  be  about  half  filled  with  the  water  to  be 
examined,  brought  into  a  horizontal  position,  level  with  the 
eye,  and  directed  toward  a  brightly  illuminated  white  sur- 
face. The  comparison  of  tint  has  to  be  made  between  the 
lower  half  of  the  tube  containing  the  water  under  examin- 
ation, and  the  upper  half  containing  air  only. 

Odor. — Put  about  150  c.  c.  of  the  water  into  a  clean, 
wide-mouth  250  c.  c.  stoppered  bottle,  which  has  been 


SANITARY    EXAMINATIONS.  19 

previously  rinsed  with  the  same  water  ;  insert  the  stopper 
and  warm  the  water  in  a  water-bath  to  100°  F.  Remove 
the  bottle  from  the  water-bath,  and  shake  it  rapidly  for  a 
few  seconds  ;  remove  the  stopper  and  immediately  note  if 
the  water  has  any  smell.  Insert  the  stopper  and  repeat  the 
test. 

In  a  polluted  water  the  odor  will  sometimes  give  a  clue 
to  the  origin  of  the  pollution. 

Reaction. — The  determination  of  reaction  is  usually 
made  by  the  addition  of  a  neutral  solution  of  litmus  to  the 
water.  If  an  acid  reaction  is  obtained  the  water  should  be 
boiled  in  order  to  determine  if  it  is  due  to  carbonic  acid. 
Some  of  the  more  delicate  indicators,  such  as  phenol- 
phthalei'n  and  lacmoid,  may  be  used  with  advantage  for 
these  tests.  The  latter  possesses  the  advantage  that  it  is 
unaffected  by  carbonic  acid,  but  detects  even  traces  of  free 
mineral  acid.  It  is  neutral,  also,  to  many  normal  metallic 
salts,  such  as  ferrous  sulphate,  which  are  acid  to  litmus.  Fer- 
ric salts,  however,  are  acid  to  lacmoid.  Its  color  changes  are 
the  same  as  those  of  litmus,  *'.  ^.,  red  with  acids  and  blue 
with  alkalies. 

Phenolphthalei'n  is  best  applied  to  the  detection  of  weak 
acids,  such  as  carbonic  acid  and  the  organic  acids.  In 
acid  and  neutral  solutions  it  is  colorless — in  alkaline,  deep 
red.  Nearly  all  waters  contain  carbonic  acid,  and  will 
therefore  bleach  a  solution  of  phenolphthalei'n  which  has 
been  reddened  by  a  small  amount  of  alkali. 

TOTAL  SOLIDS. 

A  platinum  basin  holding  100  c.  c.  will  be  found  con- 
venient for  this  determination.  This  should  weigh  about 
45  grams.  It  should  be  kept  clean  and  smooth  by  frequent 


20  ANALYTICAL   OPERATIONS. 

burnishing  with  sand,  a  little  of  which  should  be  placed 
in  the  palm  of  the  hand,  moistened,  and  the  dish  gently 
rubbed  against  it.  Very  fine  sea  sand  with  round,  smooth 
grains  is  the  only  kind  suitable  for  this  purpose.  Coarse 
river  sand,  tripoli,  or  other  rough  scouring  powders,  must 
not  be  employed.  If  proper  care  is  taken,  the  lustre  of 
the  metal  will  remain  unimpaired  indefinitely,  and  the  loss 
in  weight  will  be  trifling.  The  inner  surface  can  generally 
be  cleaned  by  treatment  with  hydrochloric  acid,  rinsing 
and,  if  necessary,  burnishing.  Neglect  of  these  precautions 
will  soon  lead  to  serious  damage  to  the  dish.  A  small, 
smooth  slab  of  iron  or  marble*  is  convenient  to  set  it  on 
while  cooling.  When  being  heated  over  the  naked  flame 
the  dish  should  rest  on  a  triangle  of  iron  wire,  covered 
with  pipe-stems.  The  dishes  of  pure  nickel  have  not  been 
found  by  us  to  be  satisfactory  substitutes  for  those  of 
platinum. 

Platinum-pointed  forceps  should  be  used  in  handling  the 
dish.     The  platinum   terminals  may  be  kept  bright  and 
FlG  2  clean  by  the  use  of  sand. 

The  low-temperature  burner, 
used  as  shown  in  Fig.  2,  will  be 
found  a  very  convenient  substi- 
tute for  the  water-bath  and  hot 
air  oven.  The  inlet  pipe  is  very 
short  and  soon,  becomes  so  hot 
as  to  injure  the  rubber  tube.  To 
avoid  this  it  may  be  lengthened 
by  means  of  a  piece  of  y%  inch 
gas-pipe,  or  the  junction  may  be 
wrapped  with  a  rag,  the  ends  of  which  dip  into  water.  By 
capillary  attraction  the  rag  is  kept  moist  and  cool. 


SANITARY    EXAMINATIONS.  21 

The  determination  of  total  solids  is  made  by  evaporating 
50  or  100  c.  c.  of  the  water  in  the  platinum  basin,  which  has 
been  previously  heated  almost  to  redness,  allowed  to  cool 
for  ten  minutes,  and  weighed.  The  operation  is  conducted 
at  a  moderate  heat.  When  the  residue  appears  dry,  the 
heat  may  be  increased  slightly  for  some  minutes.  The 
above  method  will  answer  in  most  cases.  In  waters  of  ex- 
ceptional purity  it  may  be  advisable  to  use  larger  quantities, 
such  as  250  c.  c.  When  the  residue  contains  deliquescent 
bodies,  the  determination  will  not  be  accurate,  and  when 
bodies  are  present  which  take  up  much  water  of  crystalliza- 
tion, the  residue  will  need  to  be  strongly  heated,  if  con- 
trol figures  are  to  be  obtained.  This  determination  of 
total  solids  is  described  in  connection  with  the  technical 
examinations. 

After  the  weight  of  the  residue  is  obtained,  the  dish 
should  be  cautiously  heated  to  low  redness,  and  the  effect 
noted.  Nitrates  and  nitrites,  calcium  and  magnesium  car- 
bonates, and  magnesium  chloride  are  decomposed ;  ammo- 
nium salts  are  driven  off;  potassium  and  sodium  chlo- 
rides are  also  driven  off  if  the  temperature  is  high. 
Organic  matter  is  at  first  charred,  and  by  continued  heat- 
ing burned  off.  When  the  quantity  of  nitrates  is  consider- 
able, slight  deflagration  may  be  observed,  or  the  produc- 
tion of  red  fumes  of  nitrogen  dioxide.  The  organic 
matter,  in  decomposing,  not  infrequently  develops  odors 
which  indicate  its  character  or  source.  These  are  more 
satisfactorily  observed,  when  a  rather  large  quantity,  say 
250  c.  c.,  is  evaporated  at  a  low  heat,  preferably  on  a  water- 
bath. 

In  water  of  high  organic  purity,  the  residue  on  heating 
will  give  no  appreciable  blackening  nor  odor,  while  in 


22  ANALYTICAL  OPERATIONS. 

forest  streams  charged  with  vegetable  matter  derived  from 
falling  leaves,  very  decided  blackening  without  unpleasant 
odor  will  be  noticed.  The  loss  of  weight  after  heating 
cannot  be  taken  as  a  measure  of  the  organic  matter, 
except  when  present  in  relatively  large  amount. 

CHLORINE. 
Solutions  Required : — 

Standard  Silver  Nitrate. — Dissolve  about  5  grams  of 
pure  recrystallized  silver  nitrate  in  distilled  water,  and 
make  the  solution  up  to  1000  c.  c.  The  amount  of  chlorine 
to  which  this  is  equivalent  may  be  determined  as  follows : 
Several  grams  of  pure  sodium  chloride  are  finely  powdered 
and  heated  over  a  Bunsen  burner  for  five  minutes,  not  quite 
to  redness.  When  cold,  0.824  gram  is  dissolved  in  water 
and  the  solution  made  up  to  500  c.  c.  25  c.  c.  of  this  should 
be  treated  as  below,  and  the  amount  of  silver  solution  re- 
quired noted.  Each  c.  c.  of  the  sodium  chloride  solution  is 
equivalent  to  .001  gram  chlorine. 

Potassium  Chromate. — 5  grams  of  potassium  chromate  are 
dissolved  in  looc.  c.  of  distilled  water.  A  solution  of  silver 
nitrate  is  added  until  a  permanent  red  precipitate  is  pro- 
duced, which  is  separated  by  filtration. 
Analytical  Process:  — 

If  a  preliminary  test  shows  the  chlorine  to  be  present  in 
considerable  amount,  the  determination  may  be  made  on 
TOO  c.  c.  of  the  water  without  concentration.  If,  however, 
there  is  but  little  present,  250  c.  c.  should  be  evaporated  to 
about  one-fifth,  and  the  determination  made  on  the  con- 
centrated liquid  after  cooling. 

The  water  is  placed  in  a  porcelain  dish  or  in  a  beaker 
standing  on  a  white  surface,  a  few  drops  of  potassium 


SANITARY    EXAMINATIONS.  23 

chromate  solution  added,  and  standard  silver  nitrate 
solution  run  in  from  a  burette  until  a  faint  red  color  of 
silver  chromate  remains  permanent  on  stirring.  The  pro- 
portion of  chlorine  is  then  calculated  from  the  number 
of  c.  c.  of  silver  solution  added.  For  greater  accuracy  a 
second  determination  may  be  made,  using  as  a  comparison 
thev  Iftfuid  first  titrated,  the  red  color  having  been  pre- 
viously discharged  by  a  few  drops  of  sodium  chloride 
solution. 

The  water  should  always  be  as  nearly  neutral  as  possible 
before  titration.  If  acid,  it  must  be  neutralized  by  the 
addition  of  some  precipitated  calcium  carbonate. 

NITROGEN  IN  AMMONIUM  COMPOUNDS  AND  IN  OR- 
GANIC MATTER. 

The  nitrogen  in  ammonium  compounds,  and  a  part  of 
that  in  the  organic  matter,  is  determined  by  a  process 
of  distillation  first  developed  fully  by  Messrs.  Wanklyn, 
Chapman  and  Smith.  It  depends  upon  the  conversion  of 
the  nitrogen  into  ammonia  and  subsequent  estimation  in 
the  distillate. 

Apparatus  Required : — 

Distilling  Apparatus. — That  shown  in  Fig.  3  has  been 
found  to  be  the  most  convenient.  The  still  consists  of  a 
Bohemian  glass  retort  of  about  1000  c.  c.  capacity.  The 
beak  of  the  retort  should  incline  slightly  upward,  to  prevent 
contamination  by  splashing.  At  about  two  inches  from 
the  end  it  should  be  bent  at  a  right  angle,  and  drawn  out 
so  as  to  enter  the  condensing  worm  for  about  an  inch,  and 
terminate  beneath  the  level  of  the  water.  Glass  worms  are 
apt  to  crack,  and  it  is  more  satisfactory  to  use  one  of  block 
tin.  A  piece  of  rubber  tubing  is  drawn  over  the  junction. 


24  ANALYTICAL   OPERATIONS. 

A  rapid  current  of  cold  water  should  be  maintained  through 
the  condenser.  The  heat  is  applied  by  means  of  the  low- 
temperature  burner,  the  iron  ring  of  which  is  removed  so 
that  the  retort  rests  directly  on  the  gauze.  With  this 


FIG.  3. 


arrangement  the  heat  is  under  perfect  control,   and*  the 
danger  of  fracturing  the  glass  is  reduced  to  a  minimum. 

Cylinders  for  Comparison- Color  Tests,  about  2.5  cm.   in 
diameter  and  holding  TOO  c.  c.,  made  of  colorless  glass. 
Solutions  Required  : — 

Sodium  Carbonate. — 50  grams  of  pure  sodium  carbonate 


SANITARY    EXAMINATIONS.  25 

are  strongly  heated,  dissolved  in  250  c.  c.  of  distilled  water, 
and  the  solution  boiled  down  to  200  c.  c. 

Ammonium- Free  Water. — If  the  distilled  water  of  the 
laboratory  gives  a  reaction  with  Nessler's  reagent,  it  should 
be  treated  with  sodium  carbonate,  about  one  grain  to  the 
liter,  and  boiled  until  about  one-fourth  has  been  evapor- 
ated. Ammonium-free  water  may  be  obtained  by  distill- 
ing in  a  retort,  water  made  slightly  acid  with  sulphuric 
acid. 

Standard  Ammonium  Chloride. — Dissolve  0.382  gram  of 
pure  dry  ammonium  chloride  in  100  c.  c.    of  ammonium- 
free   water.     For  use,  dilute  i  c.  c.    of  this   solution  with 
pure  water  to  100  c.  c.     i  c.  c.  of  this  dilute  solution  ccfti^* 
tains  .00001  gram  of  nitrogen. 

Nessler's  Reagent. — Dissolve  35  grams  of  potassium 
iodide  in  100  c.  c.  of  water.  Dissolve  17  parts  of  mer- 
curic chloride  in  300  c.  c.  of  water.  The  liquids  FlG  4> 
may  be  heated  to  aid  solution,  but  must  be  cooled 
before  use.  Add  the  mercuric  chloride  solution 
to  that  of  the  potasssum  iodide,  until  a  permanent 
precipitate  is  produced.  Then  dilute  with  a  20 
per  cent,  solution  of  sodium  hydroxide  to  1000 
c.  c.,  add  mercuric  chloride  solution  until  a  per- 
manent precipitate  again  forms  and  allow  to  stand 
untiUclear.  Nessler's  and  other  reagents  are  best  kept  in 
glass-capped  bottles,  Fig.  4,  in  which  the  pipette  may  re- 
main when  not  in  use.  The  solution  improves  by  keeping. 

Alkaline  Potassium  Permanganate. — Dissolve  200  grams 
of  potassium  hydroxide,  in  sticks,  and  8  grams  of  potas- 
sium permanganate,  in  a  liter  of  distilled  water. 

The  solution  is  boiled  until  about  one-fourth  is  evapo- 
rated ;    then    made  up   to   a  liter    with    ammonium-free 
c 


26  ANALYTICAL   OPERATIONS. 

water.  Since  it  will  still  furnish  some  ammonia,  it  is  ne- 
cessary to  determine  the  amount.  Fox  recommends  to  dis- 
till 5oc.c.  with  500  c.c.  of  absolutely  ammonium-free  water, 
best  twice  distilled  with  sulphuric  acid,  and  note  the  am- 
monia obtained.  This  quantity  should  be  deducted  in 
each  analysis. 
Analytical  Process  : — 

The  retort  and  condenser  are  thoroughly  rinsed  with  am- 
monium-free water,  500  c.  c.  of  the  water  to  be  tested  in- 
troduced, about  5  c.  c.  of  the.  sodium  carbonate  solution 
j*«Wed  to  render  the  w^ater  alkaline,  and  a  piece  of  pumice- 
stone  heated  to  redneSNu^i  dropped  in  while  hot.  The 
^Ster  is  then  boiled  gently  until  the  distillate  measures 
50  c.  c.  The  distillate  is  transferred  to  one  of  the  color- 
comparison  cylinders  and  2  c.  c.  of  the  Nessler's  reagent 
added.  A  yellowish-brown  color  is  produced,  the  intensity 
of  which  is  proportional  to  the  amount  of  NH3,  present. 
The  full  color  is  developed  in  five  minutes.  This  color  is 
exactly  matched  by  introducing  into  another  cylinder 
50  c.  c.  of  ammonium-free  water,  some  of  the  standard 
ammonium  chloride  solution,  and  2  c.  c.  Nessler's  reagent, 
as  before.  According  as  the  color  so  produced  is  deeper 
or  lighter  than  that  obtained  from  the  water,  other  compari- 
son liquids  are  prepared  containing  smaller  or  larger  pro- 
portions of  the  ammonium  chloride,  until  the  proper  tolor 
is  produced. 

The  distillation  is  continued,  successive  portions  of 
50  c.  c.  each  collected,  and  tested  until  no  reaction  occurs 
with  Nessler's  reagent.  The  sum  of  the  figures  from  the 
several  distillates  gives  the  total  nitrogen  obtainable  as 
/'free  ammonia/'  so-called. 

If  the  quantity  of  ammonia  is  sufficient  to  cause  a  precipi- 


SANITARY    EXAMINATIONS.  27 

tate,  the  color  comparison  cannot  be  accurately  made.  In 
most  cases  this  will  not  be  of  serious  moment,  as  the  quan- 
tity will  be  beyond  the  allowable  limit.  If  accurate  deter- 
mination be  desired,  it  may  be  made  by  dividing  the  first 
distillate  into  two  equal  parts,  nesslerizing  one  of  these, 
and  then,  if  necessary,  diluting  the  second  part  with  ammo- 
nium-free water  and  nesslerizing  this. 

Occasionally  the  evolution  of  ammonia  continues  indefi- 
nitely, and  may  even  increase  with  successive  distillates. 
This  is  due,  not  to  ammonium  compounds  existing  as 
such,  but  to  decomposition  of  certain  nitrogenous  bodies, 
especially  urea.  In  this  case,  it  is  not  advisable  to  prolong 
distillation  beyond  the  fourth  or  fifth  distillate,  but  to  pro- 
ceed to  the  following  part  of  the  process. 

The  residue  in  the  retort  serves  for  the  determination  of 
the  nitrogen  which  is  convertible  into  ammonia  by  alkaline 
potassium  permanganate — the  so-called  "albuminoid  am- 
monia" of  Messrs.  Wanklyn,  Chapman  and  Smith. 

50  c.  c.  of  alkaline  permanganate  solution  are  added  to 
the  retort,  the  distillation  resumed,  and  the  nitrogen  esti- 
mated in  each  50  c.  c.  as  before,  deducting  that  yielded  by 
the  permanganate. 

It  is  the  practice  of  some  analysts  to  mix  the  distillates 
of  each  of  the  above  operations,  and  thus  make  determina- 
tions merely  of  the  total  nitrogen  in  each  case.  By  so 
doing  valuable  information  may  be  lost,  since  it  has  been 
pointed  out  by  several  observers,  notably  Mallet  and  Smart, 
that  important  information  maybe  gained  by  observing  the 
rate  of  evolution  of  the  ammonia.  Mallet  has  further 
pointed  out  that  many  waters  may  contain  substitution 
ammoniums  which  may  pass  over  before  the  addition  of  the 
alkaline  permanganate,  but  not  be  correctly  measured  by 


28  ANALYTICAL   OPERATIONS. 

nesslerizing.  To  avoid  this  source  of  error,  he  suggested 
that  two  determinations  be  made  on  each  sample,  one  as 
above  described  and  the  other  by  the  addition  of  alkaline 
permanganate  without  previous  distillation.  In  this  man- 
ner a  higher  figure  will  often  be  obtained  than  the  sum  of 
the  figures  from  the  two  distillations  by  the  other  process. 

Since  small  quantities  of  ammonium  compounds  and 
nitrogenous  matters  are  everywhere  present,  the  greatest 
care  should  be  exercised  in  order  to  avoid  their  introduc- 
tion in  any  way  during  the  course  of  the  analysis.  All 
measuring  vessels,  cylinders,  etc.,  should  be  thoroughly 
rinsed  before  using. 

The  Chemical  Section  of  the  American  Association  for  the 
Advancement  of  Science  recommends  the  following  method 
for  the  application  of  the  "ammonia  process,"  embodying 
the  results  of  recent  investigations  : — 

"  200  c.  c.  of  distilled  water,  together  with  10  c.  c.  of 
the  sodium  carbonate  solution,  are  distilled  down  to  about 
100  c.  c.  in  the  retort  in  which  the  analysis  is  to  be  con- 
ducted, and  the  last  portion  of  50  c.  c.  nesslerized  to  assure 
freedom  from  ammonia.  Then  500  c.  c.  of  the  water  to  be 
examined  are  added  and  the  distillation  is  carried  on  at  such 
a  rate  that  about  50  c.  c.  are  collected  in  each  succeeding 
ten  minutes,  and  until  a  50  c.  c.  measure  of  distillate  is 
obtained  containing  only  an  inappreciable  quantity  of  am- 
monia. In  nesslerizing,  five  minutes  are  to  be  allowed  for 
the  full  development  of  color ;  after  this,  no  change  takes 
place  for  many  hours. 

"Now  throw  out  the  contents  of  the  retort,  rinse  it 
thoroughly,  put  in  200.  c.  c.  of  distilled  water  and  50  c.  c. 
of  the  permanganate  solution,  distill  down  to  about  100  c.  c., 
and  nesslerize  the  last  portion  of  50  c.  c.,  to  make  sure  of 


SANITARY    EXAMINATIONS. 


29 


FIG.  5. 


freedom  from  ammonia;  add  another  portion  of  500  c.  c. 
of  the  water  under  examination  and  proceed  with  the  dis- 
tillation and  nesslerizing  as  with  the  first  portion. 

"The  difference  between  the  'free'  ammonia  of  the 
first  operation  and  the  total  ammonia  of  the  second,  is  to 
be  taken  as  the  < albuminoid'  ammonia." 

For  nesslerizing  and  other  color  comparisons, 
many  forms  of  apparatus  have  been  proposed. 
One  of  the  simplest  is  that  devised  by  Hehner, 
shown  in  Fig.  5.  It  consists  of  a  graduated 
cylinder  with  a  stopcock  near  the  base,  by  which 
the  liquid  can  be  drawn  down  at  will.  Two  such 
cylinders  may  be  used,  one  for  the  nesslerized  dis- 
tillate, the  other  for  the  comparison  liquid.  The 
darker  liquid  is  drawn  out  until  the  tints  are 
equal,  when  the  relative  volumes  remaining  will  give  the 
data  for  calculation. 

Another  convenient  form  of  color  comparator 
is  shown  in  Fig.  6.  It  consists  of  a  box  black- 
ened inside,  and  supported  so  as  to  permit  a 
movable  mirror  to  be  mounted  underneath. 
The  box  is  perforated  at  both  ends  to  receive 
graduated  tubes  holding  60  c.  c.  A  projecting 
rim  shades  the  ends  of  the  tubes  from  extra- 
neous light. 

In  practice  the  Nessler  reagent  is  mixed  with 
50  c.  c.  of  the  distillate,  and  poured  into  one 
of  the  tubes.  The  usual  comparison  'color  is 
made  up  and  transferred  to  the  other  tube. 
The  darker  liquid  is  poured  into  the  vessel  in 
which  it  was  originally  prepared  and  then  poured 
slowly  back  into  the  tube  until  the  colors  are  equalized. 


FIG.  6. 


30  ANALYTICAL   OPERATIONS. 

This  apparatus  permits  the  use  of  amber  glass  as  a  stand- 
ard color  in  place  of  the  comparison  liquid.  Very  rapid 
and  sufficiently  accurate  determinations  can  be  made  by 
this  means.  The  amber  glass  is  standardized  as  follows :  — 

One  of  the  tubes  is  nearly  rilled  with  clear  water,  and  the 
glass  placed  across  the  top,  the  mirror  being  so  adjusted 
that  the  light  is  thrown  directly  up  the  tube.  The  equiva- 
lent of  the  color  so  produced  is  carefully  determined  by 
nesslerizing,  in  the  adjoining  tube,  a  known  amount  of  am- 
monium chloride.  The  glass  is  used  as  a  comparison  color 
by  placing  it,  as  before,  on  the  top  of  one  of  the  tubes  filled 
with  clear  water,  and  pouring  into  the  other  tube  the  dis- 
tillate mixed  with  Nessler's  reagent  until  the  colors  are 
equalized. 

For  example :  If  the  glass  is  equal  to  1.5  c.  c.  standard 
diluted  ammonium  chloride  solution,  and  in  a  given  experi- 
ment, the  tube  must  be  filled  to  40  .c.  c.  with  the  liquid 
to-be  determined  (50  c.  c.  of  distillate  and  2  c.  c.  of  Ness- 
ler)  then 

40  :  52  :  :  1.5  :  1.95.  1.95  is  the  number  of  c.  c.  of 
ammonium  chloride  solution  to  which  the  50  c.  c.  of  distil- 
late are  equal. 

TOTAL  ORGANIC  NITROGEN. 

Several  processes  for  the  determination  of  the  organic 
nitrogen  in  water,  based  on  those  in  use  in  ordinary  organic 
analysis,  have  been  devised.  That  of  Frankland  and  Arm- 
strong requires  complex  and  extensive  apparatus  and  spe- 
cial skill,  has  been  shown  also  to  be  liable  to  inaccura- 
cies, and  has  not  come  into  extended  use. 

The  ease  and  certainty  with  which  the  nitrogen  of  most 
organic  bodies  may  be  converted  into  ammonium  sulphate 


SANITARY    EXAMINATIONS.  3! 

by  boiling  with  sulphuric  acid,  offers  a  means  of  determina- 
>tion  free  from  the  objections  of  former  methods.  The 
method  introduced  by  Kjeldahl  for  general  organic  analy- 
sis, was  first  successfully  applied  to  water  analysis  by  Drown 
and  Martin  {Technology  Quarterly,  n,  3). 

In  their  original  process  500  c.  c.  was  concentrated  to 
about  300  c.  c.,  and  the  distillate  nesslerized  for  determin- 
ing the  nitrogen  existing  as  ammonium  compounds.  The 
organic  nitrogen  is  then  determined  in  the  residual  water. 
Owing  to  the  fact  that  in  many  waters  the  organic  matter 
is  decomposed  by  boiling,  there  is  liability  to  under- 
estimation of  the  nitrogen.  We  prefer,  therefore,  to  de- 
termine at  once  the  total  unoxidized  nitrogen,  and  esti- 
mate, without  distillation,  on  a  separate  portion  of  the 
sample,  the  nitrogen  that  exists  in  ammonium  compounds. 
Our  procedure  is  as  follows  : — 
Reagents  Required: — 

Concentrated  Sulphuric  Acid. — This  should  be  as  free  as 
possible  from  nitrogen.  It  can  be  obtained  containing 
only  0.015  mgm.  in  TO  c.  c. 

Sodium  Hydroxide  Solution. — The  white  granulated  caus- 
tic soda  sold  for  household  use  will  answer;  350  grams 
are  dissolved  in  water  and  made  up  to  1000  c.  c. 

Sodium  Carbonate  and  Hydroxide  Solution. — 25  grams  of 
each  are  dissolved  in  250  c.  c.  of  distilled  water,  and  the 
solution  boiled  down  to  200  c.  c.,  to  free  it  from  ammonium. 
Analytical  Process : — 

Determination  of  Nitrogen  Existing  as  Ammonium. — 200 
c.  c.  of  the  water  are  placed  in  a  stoppered  bottle,  2  c.  c. 
each  of  the  solutions  of  sodium  carbonate  and  sodium 
hydroxide  added,  the  stopper  inserted,  the  solutions  mixed 
and  allowed  to  stand  for  an  hour  or  two.  A  filter  is  pre- 


32  ANALYTICAL  OPERATIONS. 

pared  by  inserting  a  rather  large  plug  of  absorbent  cotton 
in  a  funnel.  This  should  be  washed  with  ammonium-free^ 
water  until  the  nitrate  gives  no  color  with  Nessler's 
reagent.  The  clear  portion  of  the  sample  is  drawn  off 
with  a  pipette  and  run  through  the  filter,  the  first  portions 
being  rejected,  since  it  is  diluted  by  the  water  retained  in 
the  cotton.  The  filtration  is  rapid,  and  when  100  c.  c.  of 
the  liquid  have  passed  through  it  is  nesslerized.  If  but 
little  ammonium  is  present,  a  narrow  tube  about  60  centi- 
meters long  should  be  used  for  observing  the  color. 

Estimation  of  the  Total  Organic  and  Ammoniac al  Nitro- 
gen.— 500  c.  c.  of  the  water  are  placed  in  a  round-bottomed 
Bohemian  glass  flask,  10  c.  c.  of  concentrated  sulphuric  acid 
added,  and  a  piece  of  pumice-stone  is  heated  to  bright  red- 
ness and  dropped  in  while  hot.  The  liquid  is  boiled  until 
the  acid  is  colorless  or  very  pale,  the  boiling  being 
continued  for  nearly  an  hour  from  this  point.  The  flask 
is  then  removed  from  the  flame,  allowed  to  cool,  and  about 
250  c.  c.  of  ammonium-free  water  added.  50  c.  c.  of  the 
sodium  hydroxide  solution  should  be  placed  in  the  distil- 
ling apparatus,  Fig.  3,  about  250  c.c.  of  water  added,  a  piece 
of  red-hot  pumice-stone  dropped  in  and  the  liquid  distilled 
until  the  distillate  is  free  from  ammonium.  It  is  best  to 
distill  until  the  retort  contains  not  more  than  100  c.  c. 
The  sulphuric  acid  solution  is  then  poured  in  slowly,  by 
means  of  a  funnel  the  stem  of  which  touches  the  side  of  the 
retort,  so  that  the  two  liquids  do  not  mingle.  The  stopper 
of  the  retort  is  inserted,  the  liquids  mixed  by  gentle  agita- 
tion, and  distilled.  If  much  ammonium  is  present  it  is 
advisable  to  distill  the  first  portion  into  about  10  c.  c.  of 
very  dilute  (i  :  1000)  sulphuric  acid,  a  piece  of  glass  tube 
being  connected  to  the  condensing  worm  so  that  the  lower 


SANITARY    EXAMINATIONS.  33 

end  c&ps  below  the  surface  of  the  liquid.     The  distillates 
are  collected  and  nesslerized  in  the  usual  way. 

A  blank  experiment  should  be  made  to  determine  the 
amount  of  ammonium  in  the  sulphuric  acid. 

NITROGEN  AS  NITRATES, 
Solutions  Required  :— 

Phenolsulphonic  Acid. — 37  c.  c.  of  strong  sulphuric  acid 
are  added  to  3  c.  c.  of  water  and  6  grams  of  pure  phenol. 

Standard  Potassium  Nitrate. — 0.722  gram  of  potassium 
nitrate,  previously  heated  to  a  temperature  just  sufficient 
to  fuse  it,  are'  dissolved  in  water,  and  the  solution  made  up 
to  1000  c.  c.  i  c.  c.  of  this  solution  will  contain  .0001 
grm.  of  nitrogen. 
Analytical  Process  : — 

A  measured  volume  of  the  water  is  evaporated  just  to  dry- 
ness  in  a  platinum  or  porcelain  basin,  i  c.  c.  of  the  phenol- 
sulphonic  acid  is  added  and  thoroughly  mixed  with  the 
residue  by  means  of  a  glass  rod.  i  c.  c.  of  water  is  added, 
three  drops  of  strong  sulphuric  acid,  and  the  dish  gently 
warmed  on  the  water  bath.  The  liquid  is  then  diluted 
with  about  25  c.  c.  of  water,  ammonium  hydroxide  added 
in  excess,  and  the  solution  made  up  to  100  c.  c. 

The  nitrate  converts  the  phenolsulphonic  acid  into  picric 
acid,  which  by  the  action  of  the  ammonium  hydroxide 
forms  ammonium  picrate ;  this  imparts  to  the  solution  a 
yellow  color,  the  intensity  of  which  is  proportional  to  the 
amount  present. 

One  c.  c.  of  the  standard  solution  of  potassium  nitrate  is 
now  similarly  evaporated  in  a  platinum  basin,  treated  as 
above,  and  made  up  to  100  c.  c.  The  color  produced  is 
compared  to  that  given  by  the  water,  and  one  or  the  other 


34  ANALYTICAL   OPERATIONS. 

of  the  solutions  is  diluted  until  the  tints  of  the  two  agree. 
The  comparative  volumes  of  the  liquids  furnish  the  neces- 
sary data  for  determining  the  amount  of  nitrate,  as  the  fol- 
lowing example  will  show  :  — 

The  solution  from  10  c.  c.  is  diluted  to  looc.  c. ;  i  c.  c. 
of  the  standard,  equal  to  .0001  of  N,  requires,  after  treat- 
ment, dilution  to  200  c.  c.  to  match  the  color.  .  Then 
200  :  100  :  :  .0001  :  x.  x.  =  .00005  =  N.  in  10  c.  c.  — 
.005  N.  in  1000  c.  c. 

Since  ammonium  picrate  solution  keeps  well  in  the  dark, 
a  good  plan  is  to  make  a  solution,  equivalent  to,  say,  ten 
milligrams  of  nitrogen  as  nitrate  per  liter,  to  which  the 
color  obtained  from  the  water  may  be  directly  compared. 

The  results  obtained  by  this  method  are  accurate.  Care 
should  be  taken  that  the  same  quantities  of  phenolsulphonic 
acid  are  used  for  the  water  and  for  the  comparison  liquid. 

With  subsoil  and  other  waters  probably  containing  much 
nitrates,  10  c.  c.  will  be  sufficient ;  but  with  river  and  spring 
waters,  25  c.  c.  may  be  used.  When  the  organic  matter  is 
sufficient  to  color  the  residue,  it  will  be  well  to  purify  the 
water  by  addition  of  alum  and  subsequent  filtration,  before 
evaporating. 

The  following  is  the  process  for  determining  nitrogen  as 
nitrates  (and  nitrites)  recommended  by  the  Chemical  Sec- 
tion of  the  A.  A.  A.  S.  It  depends  upon  conversion  into 
ammonium  by  the  copper-zinc  couple,  and  subsequent 
nesslerizing. 

Take  two  wide-mouth  glass-stoppered  bottles,  each  hold- 
ing 250  c.  c.  and  a  piece  of  sheet  zinc  as  long  and  about  as 
wide  as  the  bottles  are  deep  from  the  shoulder  down  ;  clean 
the  zinc  by  dipping  in  dilute  acid  and  washing  with  water 
and  make  it  into  a  loose  coil  by  rolling  it  round  a  piece  of 


SANITARY    EXAMINATIONS.  35 

glass  tube.  Immerse  it  in  a  1.4  to  1.8  per  cent,  solution  of 
cupric  sulphate  in  ammonia-free  water,  and  leave  it  there 
until  its  surface  is  well  covered  with  a  continuous  layer  of 
the  black  copper ;  lift  it  out  carefully,  cover  it  in  a  beaker 
with  successive  portions  of  ammonia-free  water,  lifting 
it  out  and  draining  each  time,  and  at  once  put  it 
into  one  of  the  bottles  of  acidified  water,  prepared  as 
follows  :  — 

Make  500  c.  c.  of  the  water  to  be  examined  distinctly 
acid  with  oxalic  acid  added  in  fine  powder,  with  constant 
stirring,  so  that  it  shall  dissolve  readily,  and  pour  half  of 
the  liquid  into  one  of  these  250  c.  c.  bottles,  and  half  into 
the  other,  and  leave  them,  stoppered,  in  a  warm  place  for 
twenty-four  hours.  Then  nesslerize  both  samples,  decant- 
ing off  the  portions  as  wanted,  from  the  precipitated  earthy 
oxalates,  and  using  double  the  usual  quantity  of  Nessler's 
solution,  since  the  free  oxalic  acid  has  to  be  neutralized 
first  by  the  alkali  of  the  reagent.  The  proportion  of 
ammonia  may  often  be  so  large  in  the  water  in  which 
the  reduction  is  made,  by  the  copper-zinc  couple,  that 
only  five  or  ten  c.  c.  can  be  taken  for  each  test,  and  made 
up  to  50  c.  c.  by  the  addition  of  ammonia-free  water.  The 
difference  between  the  results  with  the  two  portions  of 
water,  gives  the  amount  of  nitrogen  due  to  the  oxidized 
nitrogen  compounds  in  the  water  examined. 

NITROGEN  AS  NITRITES. 

The  following  is  Ilosvay's  modification  of  Griess's  test. 
It  has  the  advantage  over  the  original  method,  that  the 
color  is  developed  more  rapidly,  and  the  solutions  are  not 
so  liable  to  change. 


36  ANALYTICAL   OPERATIONS. 

Solutions  Required  : — 

Para-amidobenzenesulphonic  Acid  (Sulphanilic  Acid). — 
Dissolve  0.5  gram  in  150  c.  c.  of  diluted  acetic  acid,  sp. 
gr.  1.04. 

a-amido-naphthalene  Acetate. — Boil  o.i  gram  of  solid 
tt-amido-naphthalene  (naphthylamine)  in  20  c.  c.  of  water, 
filter  the  solution,  through  a  plug  of  washed  absorbent 
cotton,  and  mix  the  filtrate  with  180  c.  c.  of  diluted  acetic 
acid.  All  water  used  must  be  free  from  nitrites,  and  all 
vessels  must  be  rinsed  out  with  such  water  before  tests 
are  applied,  since  appreciable  quantities  of  nitrites  may  be 
taken  up  from  the  air. 

Standard  Sodium  Nitrite. — 0.275  gram  pure  silver 
nitrite  are  dissolved  in  pure  water,  and  a  dilute  solution  of 
pure  sodium  chloride  added  until  the  precipitate  ceases  to 
form.  It  is  then  diluted  with  pure  water  to  250  c.  c.,  and 
allowed  to  stand  until  clear.  For  use  10  c.  c.  of  this  solu- 
tion are  diluted  to  100  c.  c.  It  is  to  be  kept  in  the  dark. 

One  c.  c.  of  the  dilute  solution  is  equivalent  to  .00001 
gram  nitrogen. 

The  silver  nitrite  is  prepared  thus  :  A  hot  concentrated 
solution  of  silver  nitrate  is  added  to  a  concentrated  solu- 
tion of  the  purest  sodium  or  potassium  nitrite  available, 
filtered  while  hot  and  allowed  to  cool.  The  silver  nitrite 
will  separate  in  fine  needle-like  crystals,  which  are  freed 
from  the  mother  liquor  by  filtration  by  the  aid  of  a  filter 
pump.  The  crystals  are  dissolved. .in  the  smallest  possible 
quantity  of  hot  water,  allowed  to  cool  and  again  separated 
by  means  of  the  pump.  They  are  then  thoroughly  dried 
in  the  water-bath,  and  preserved  in  a  tightly-stoppered 
bottle  away  from  the  light.  The  purity  may  be  tested  by 


SANITARY    EXAMINATIONS.  37 

heating  a  weighed  quantity  to  redness  in  a  tared  porcelain 
crucible  and  noting  the  weight  of  the  metallic  silver.     154 
parts  of  AgNO2  leave  a  residue  of  108  parts  Ag. 
Analytical  Process  :— 

25  c.  c.  of  the  water  are  placed  in  one  of  the  color-com- 
parison cylinders.  By  means  of  a  pipette,  2  c.  c.  each  of 
the  solutions  of  sulphanilic  acid  and  amido-naphthalene 
acetate  are  dropped  into  the  water.  It  is  convenient  to 
have  a  pipette  for  each  solution,  and  to  use  it  for  no  other 
purpose. 

One  c.  c.  of  the  standard  nitrite  solution  is  placed  in 
another  clean  cylinder,  made  up  with  nitrite-free  water  to 
25  c.  c.  and  treated  with  the  reagents  as  above. 

In  the  presence  of  nitrites  a  pink  color  is  produced.  At 
the  end  of  five  minutes  the  two  solutions  are  compared, 
the  colors  equalized  by  diluting  the  darker,  and  the  calcu- 
lation made  as  explained  under  the  estimation  of  nitrates. 

The  reactions  consist  in  the  conversion  of  the  sulphan- 
ilic acid  into  diazo-benzene  sulphonic  anhydride,  by  the 
nitrite  present ;  this  compound  is  then  in  turn  converted 
by  the  amido-naphthalene  into  azo-a-amido-naphthalene- 
parazobenzene  sulphonic  acid.  The  last-named  body  gives 
the  color  to  the  liquid. 

OXYGEN-CONSUMING  POWER, 

All  organic  materials  being  more  or  less  easily  oxidized, 
several  methods  have  been  suggested  for  determining  the 
oxygen-consuming  powers  of  waters  by  treatment  with 
active  oxidizing  agents.  These  methods  are,  however, 
limited  in  value.  The  organic  matters  in  water  differ 
much  in  character  and  condition,  and  their  oxidability  is 
subject  to  much  variation,  according  to  the  circumstances 


38  ANALYTICAL   OPERATIONS. 

under  which  the  test  is  made.  Nevertheless,  as  a  high 
oxygen-consuming  power  certainly  indicates  departure  from 
purity,  some  additional  evidence  may  be  obtained.  Potas- 
sium permanganate  is  especially  suitable.  The  test  is 
usually  made  by  introducing  a  known  amount  of  the  per- 
manganate into  the  water,  which  has  been  rendered  acid, 
and  measuring  after  a  definite  period  the  proportion  which 
has  been  decomposed. 

It  must  not  be  overlooked  that  if  a  water  contains 
nitrites,  ferrous  compounds,  or  sulphur  compounds  other 
than  sulphates,  the  proportion  of  oxygen  consumed  will  be 
greater  than  that  required  for  the  organic  matter.  It  has 
been  proposed,  in  order  to  remove  the  nitrites  before 
applying  the  permanganate,  to  take  500  c.  c.  of  the  water, 
add  10  c.  c.  of  the  dilute  sulphuric  acid,  boil  for  twenty 
minutes,  allow  to  cool,  and  then  treat  with  permanganate. 
Since,  however,  the  amount  of  nitrites,  if  appreciable,  can 
be  directly  determined,  it  is  more  satisfactory  to  deduct 
from  the  oxygen  consumed  the  amount  required  to  con- 
vert the  nitrites  present  into  nitrates,  and  the  remainder 
will  be  that  required  for  the  other  oxidizable  ingredients. 
14  parts  of  nitrogen  existing  as  nitrite  require  16  parts  of 
oxygen  for  conversion  into  nitrate.  Similarly,  112  parts 
of  iron  in  a  ferrous  compound  will  require  16  parts  of 
oxygen  for  conversion  to  the  ferric  condition. 

Of  the  following  methods  the  first  is  due  in  the  main  to 
Dr.  Tidy,  has  been  improved  by  Dr.  Dupre,  and  is  ap- 
proved by  the  Society  of  Public  Analysts  of  Great  Britain  : — 
Solutions  Required : — 

Standard  Permanganate, — .395  gram  pure  potassium  per- 
manganate are  dissolved  in  distilled  water,  and  the  solution 
made  up  to  1000  c.  c.  i  c.  c.  is  equal  to.  oooi  gram  oxygen. 


SANITARY  EXAMINATIONS.  39 

Diluted  Sulphuric  Acid. — Add  50  c.  c.  of  pure  sulphuric 
acid  to  100  c.  c.  of  water,  and  then  add  solution  of  potas- 
sium permanganate  until  a  faint  pink  color  is  obtained, 
which  is  permanent  when  the  liquid  is  heated  to  80° 
Fahrenheit  for  four  hours. 

Potassium  Iodide. — 10  grams  of  the  pure  salt  recrystal- 
lized  from  alcohol  are  dissolved  in  100  c.  c.  of  distilled 
water. 

Sodium  Thiosulphate. — i  gram  of  the  pure  crystallized 
salt  dissolved  in  2000  c.  c.  of  distilled  water. 

Starch  Indicator. — i  gram  of  clean  starch  is  mixed 
smoothly  with  cold  water  into  a  thin  paste,  then  poured 
gradually  into  about  200  c.  c.  of  boiling  water,  the  boiling 
continued  for  one  minute,  the  liquid  allowed  to  settle,  and 
the  clear  portion  used.  It  is  best  freshly  prepared. 
Analytical  Process  : — 

Two  determinations  are  made,  one,  of  the  oxygen  con- 
sumed in  fifteen  minutes,  which  is  considered  to  represent 
the  nitrites,  sulphides  or  ferrous  compounds,  and  the  other 
of  the  oxygen  consumed  by  four  hours'  action.  Both  de- 
terminations are  made  at  a  temperature  of  80°  F.  Three 
glass- stoppered  bottles,  of  about  350  c.  c.  capacity,  are 
rinsed  with  strong  sulphuric  acid,  and  then  with  water.  In 
one  is  placed  250  c.  c.  of  pure  distilled  water  as  a  control 
experiment,  and  in  each  of  the  others  250  c.  c.  of  the  water 
to  be  tested.  The  bottles  are  stoppered,  and  brought  to  a 
temperature  of  80  F. ;  10  c.  c.  of  the  dilute  sulphuric  acid 
and  10  c.  c.  of  the  standard  permanganate  are  added  to 
each  and  the  stoppers  again  replaced.  At  the  end  of 
fifteen  minutes  one  sample  of  water  is  removed  from  the 
bath,  and  two  or  three  drops  of  the  potassium  iodide  solu- 
tion added  to  remove  the  pink  color.  After  thorough 


40  ANALYTICAL  OPERATIONS. 

admixture,  the  thiosulphate  solution  is  run  in  from  a  burette 
until  the  yellow  color  is  nearly  destroyed,  a  few  drops  of 
the  starch  solution  added,  and  the  addition  of  the  thiosul- 
phate continued  until  the  blue  color  is  quite  discharged. 
If  the  addition  of  the  thiosulphate  solution  has  been 
properly  conducted,  one  drop  of  the  permanganate  solu- 
tion will  restore  the  blue  color. 

The  other  bottles  are  maintained  at  80°  F.  for  four  hours. 
Should  the  pink  color  disappear  rapidly  in  the  bottle  con- 
taining the  water  under  examination,  10  c.  c.  of  the  per- 
manganate solution  must  be  added  to  each  bottle,  in  order 
to  maintain  a  distict  pink  color.  At  the  end  of  four  hours 
each  bottle  is  removed  from  the  bath,  two  or  three  drops 
of  potassium  iodide  added,  and  the  titration  with  thiosul- 
phate solution  conducted  as  just  described.  The  calcu- 
lation is  most  conveniently  made  as  follows: — 

a  =  number  of  c.  c.  required  for  the  control  experiment. 

b  =  number  of  c.  c.  required  for  the  water  under  exami- 
nation. 

c  =  available  O  in  permanganate  (.001  for  10  c.  c.) 

x  =  oxygen  consumed  by  water. 

Then,  a  :  a-b  \\c\x. 

The  following  method  is  recommended  by  the  Chemical 
Section  of  the  American  Association  for  the  Advancement 
of  Science : — 

''Prepare  a  solution  of  potassium  permanganate  contain- 
ing o.i  mgm.  of  available  oxygen  to  one  c.  c.  and  a  solu- 
tion of  oxalic  acid  of  such  strength  as  to  decompose  the 
permanganate  solution,  volume  for  volume,  the  strength 
being  re-determined  from  time  to  time.  The  water  used 
for  making  these  solutions  should  be  purified,  by  distillation 
from  alkaline  permanganate. 


SANITARY     EXAMINATIONS.  41 

"To  200  c.  c.  of  water  to  be  examined,  in  a  400  c.  c. 
flask,  add  10  c.  c.  of  dilute  sulphuric  acid  (i  :  3)  and  such 
measured  quantity  of  the  permanganate  as  will  give  a  per- 
sistent color;  boil  ten  minutes,  add,  if  necessary,  more 
permanganate  in  measured  quantities  so  as  to  maintain  the 
red  color;  remove  the  flask  from  the  lamp,  add  jo  c.  c.  of 
oxalic  acid  solution  to  destroy  the  color,  or  more  if 
required  by  the  excess  of  permanganate,  and  then  add  per- 
manganate, drop  by  drop,  till  a  faint  pink  tint  appears. 
From  the  total  quantity  of  permanganate  used  deduct  the 
equivalent  of  the  oxalic  acid  used,  and  from  the  remainder 
calculate  the  milligrams  of  oxygen  consumed  by  the  oxid- 
izable  orgfcnic  matter  in  the  water." 

The  oxygen-consuming  power  may  also  be  indirectly 
estimated  by  the  action  of  the  organic  matter  upon  silver 
compounds.  H.  Fleck's  method  (JFresenius*  Quantitative 
Analysis,  English  edition,  vol.  n,  /.  127)  depends  upon 
the  reduction  produced  by  boiling  the  water  with  alkaline 
solution  of  silver  thiosulphate  and  estimation  of  the  unre- 
duced silver.  A.  R.  Leeds  (Lond.,  Edin.  and  Dub.  Phil. 
Mag.,  Jiily^  1883}  gives  a  method  by  treating  the  water 
with  decinormal  silver  nitrate,  exposing  to  light  until  it 
settles  perfectly  clear,  and  estimating  the  reduced  silver  in 
the  deposit. 

These  methods  are  open  to  practically  the  same  objections 
as  in  the  use  of  permanganate,  and  do  not  seem  to  possess 
any  decided  advantage.  Qualitative  results  of  some 
interest  may  occasionally  be  obtained  by  the  following 
method  :  2  c.  c.  of  a  one  per  cent,  solution  of  silver  nitrate, 
rendered  decidedly  alkaline  by  ammonium  hydroxide,  are 
added  to  100  c.  c.  of  the  water  in  a  stoppered  bottle,  which 
is  then  placed  in  full  sunlight  for  two  hours.  Waters  con- 

D 


42  ANALYTICAL  OPERATIONS. 

taming  but  little  organic  matter  will  not  show  at  the  end  of 
this  period  any  appreciable  tint.  The  following  results  will 
show  the  character  of  the  test : — 

Schuylkill  water, no  color. 

"  "     with  0.02  c.  c.  urine,    .    .    .  red-brown. 

"  *          "     with  o.oi   c.  c.  urine,    .    .    .  deep  brown. 
"  "     with  0.25  gram  raw  sugar,   .  no  color. 

Well  water,  not  perfectly  pure,  but 

not  unfit  to  drink, faint  black. 

"          "      markedly   contaminated,     .    .    .  black  ppt.  almost 

immediately. 
Water  from  a  small  stream,  quite  pure  ...  no  color. 

• 
PHOSPHATES. 

Solutions  Required:  — 

Ammonium  Molybdate. — Ten  grams  of  molybdic  anhy- 
dride are  dissolved  in  41 . 7  c.  c.  of  ammonium  hydroxide,  sp. 
gr.  0.96,  and  the  solution  is  poured  slowly,  and  with  con- 
stant stirring,  into  125  c.  c.  of  nitric  acid,  sp.  gr.  1.20, 
and  allowed  to  stand  in  a  warm  place  for  several  days,  until 
clear.  ^ 

Analytical  Process : — 

500  c.  c.  of  the  water  are  slightly  acidified  with  nitric  acid, 
and  evaporated  to  about  50  c.  c.  A  few  drops  of  dilute 
solution  of  ferric  chloride  are  added  and  then  ammonium 
hydroxide  in  slight  excess.  The  precipitate,  which  con- 
tains all  the  phosphate,  is  filtered  off  and  dissolved  on  the 
filter  by  the  smallest  possible  quantity  of  hot  dilute 
nitric  acid.  The  filtrate  and  washings  should  not  exceed 
5  c.  c.;  if  more,  they  must  be  evaporated  to  this  bulk.  The 
liquid  is  heated  nearly  to  boiling,  2  c.  c.  of  ammonium 
molybdate  solution  added,  and  the  liquid  kept  moderately 


SANITARY    EXAMINATIONS.  43 

warm  for  half  an  hour.  If  the  quantity  of  precipitate  is 
appreciable,  it  is  collected  on  a  small  weighed  filter,  washed 
with  distilled  water,  dried  at  100°  F.  and  weighed.  The 
weight  of  the  precipitate  multiplied  by  0.05  gives  the 
amount  of  PO4.  If  the  quantity  is  not  sufficient  to  collect 
in  this  manner,  it  is  usually  reported,  according  to  cir- 
cumstances, as  "traces,"  "  heavy  traces,"  or  "very  heavy 
traces." 

SUGAR-TEST. 

This  method  was  proposed  by  Heisch  for  the  detection 
of  a  fungus  supposed  to  be  peculiar  to  sewage.  It  con- 
sists in  adding  to  the  water  a  small  quantity  of  sugar,  in 
which  the  fungus  grows  with  great  rapidity.  The  test  is 
applied  as  follows  :  — 

A  stoppered  bottle  of  about  100  c.  c.  capacity  is  rinsed 
thoroughly  with  the  water  to  be  tested,  filled  with  the  clear 
water,  about  half  a  gram  of  pure  crystallized  sugar  added 
and  the  stopper  inserted.  The  bottle  is  placed  in  a  strong 
light,  and  kept  at  a  temperature  of  about  80°  F.  At  the 
end  of  several  hours  it  is  examined  for  the  fungus,  which, 
in  a  good  side  light,  with  the  bottle  against  a  dark  back- 
ground, is  generally  easily  visible  as  a  distinct  turbidity. 
If  examined  under  a  power  of  250  diameters,  it  is  found 
to  consist  of  small  spherical  cells,  having  in  most  cases  a 
bright  nucleus.  After  the  lapse  of  some  days  these  gradually 
group  themselves  together  something  like  grapes;  they 
next  spread  out  into  strings,  with  a  surrounding  wall  con- 
necting the  cells  together ;  the  original  cells  then  seem  to 
break  and  leave  apparently  tubular  threads  joined  by 
branches.  In  the  more  marked  cases  the  development  of 
the  fungus  is  accompanied  by  a  distinct  odor  of  butyric 
acid.  Hydrogen  sulphide 'and  other  gases  are  also  some- 


44  ANALYTICAL  OPERATIONS. 

times  formed.  These  odors  do  not  generally  appear  until 
after  twenty-four  hours  or  longer.  Heisch  concluded  that 
the  cells  thus  developed  were  distinct  evidence  of  sewage 
contamination,  but  such  microorganisms  are  found  in  all 
waters  that  have  been  exposed  even  momentarily  to  air, 
and  Frankland  has  shown  that  their  development  under 
these  conditions  is  due  to  the  presence  of  phosphates.  He 
found  that  the  addition  even  of  minute  traces  of  a  phos- 
phate, either  as  sodium  phosphate,  white  of  egg,  or  animal 
charcoal,  at  once  determined  the  growth  in  saccharine 
liquids  which,  before,  exhibited  no  tendency  to  develop 
them. 

DISSOLVED   OXYGEN. 

The  method  here  given,  a  modification  of  Mohr's,  was  . 
proposed  by  Blarez.     Our  experiments  indicate  that  it  is 
rapid  and  satisfactory. 
Solutions  Required : — 

Sodium  Hydroxide. — 40  grams  of  pure  sodium  hydroxide 
to  the  liter. 

Ferrous-Ammonium  Sulphate. — 40  grams  dissolved  in 
about  a  liter  of  water,  and  acidified  with  a  few  drops  of 
concentrated  sulphuric  acid. 

Decinormal  Potassium  Permanganate. — 3.156  grams  dis- 
solved in  a  liter  of  distilled  water.  The  accuracy  of  this 
solution  should  be  determined  by  titration  with  a  known 
weight  of  ferrous-ammonium  sulphate.  One  c.  c.  should 
be  equivalent  to  .0392  grm.  ferrous-ammonium  sulphate 
(.0008  gram  of  oxygen). 

The  apparatus  employed  (shown  in  Fig.  7)  is  a  globular 
separator,  of  about  250  c.  c.  capacity.  Above  the  bulb  is 
a  caoutchouc  stopper  carrying  a  cylindrical  funnel,  of 
about  12  c.  c.  capacity,  terminating  in  a  tube,  y$  inch 


SANITARY    EXAMINATIONS.  45 

calibre,   sharply  contracted  at   the    outlet  to  a   capillary 
opening.     The  tube   should  project  about  ^  inch  below 
the  stopper.     The  exact  capacity  of  the  appa- 
ratus is  measured  as  follows  :  The  bulb  is  com- 
pletely   filled    with    water    and    the    stopper 
inserted ;    the    level    of    the    water   will    rise 
slightly    in    the  funnel    tube,    and    should    be 
brought  down  to  its  outlet  by  drawing  a  little 
off  at   the  stopcock,  after  which   the  water  is 
run  into  a  graduated   measure  and  its  volume 
noted. 
Analytical  Process  :— 

35  c.c.  of  mercury  and  10  c.  c.  of  sodium 
hydroxide  solution  are  put  into  the  bulb, 
and  then  sufficient  of  the  water  to  be  tested 
to  fill  it.  The  funnel  stopper  is  inserted  and  the  water 
which  rises  into  the  funnel  brought  into  the  bulb  by 
cautiously  running  out  at  the  stopcock,  mercury,  the 
volume  of  which  should  be  noted.  The  exact  volume 
of  water  used  is  thus  known.  Five  c.  c.  of  the  ferrous- 
ammonium  sulphate  solution  are  poured  into  the  funnel, 
brought  into  the  bulb  by  running  out  mercury,  and  the 
liquid  thoroughly  mixed  by  giving  the  apparatus  a  gyratory 
movement.  After  standing  five  or  six  minutes  the  oxygen 
will  be  completely  absorbed;  10  c.  c.  of  the  diluted  sul- 
phuric acid  are  now  added  by  the  same  method.  On 
agitating  the  bulb  the  contents  become  clear.  'The  watery 
liquid  is  then  transferred  to  a  beaker  and  titrated  with  deci- 
normal  permanganate.  A  volume  of  water  equal  to  that 
used  in  the  test  is  poured  into  another  beaker,  10  c.  c.  each 
of  the  sodium  hydroxide  and  diluted  sulphuric  acid  added, 
and  then  5  c.  c.  of  ferrous-ammonium  sulphate  solution. 


46  ANALYTICAL  OPERATIONS. 

The  resulting  liquid  is  titrated  with  permanganate.  The 
weight  of  oxygen  corresponding  to  the  difference  between 
the  two  titrations  gives  the  weight  of  dissolved  oxygen  in 
the  liquid  employed.  From  this  should  be  subtracted  as 
correction  the  amount  of  oxygen  dissolved  by  a  volume  of 
water  equal  to  that  of  the  sodium  hydroxide  solution  used. 
This  is  found  by  reference  to  the  table  in  the  appendix. 
The  amount  of  dissolved  oxygen  in  the  sulphuric  acid  has 
no  appreciable  effect. 

Nitrates  do  not  appear  to  impair  the  accuracy  of  this 
method,  and  the  interfering  action  of  nitrites  and  other 
reducing  compounds  is  avoided  by  the  control  experiment 
as  detailed. 

It  is  perhaps  hardly  necessary  to  add  that  the  exact 
temperature  of  the  water  is  to  be  noted  at  the  time  of 
collection  of  the  sample. 

In  transferring  to  the  bulb,  the  water  should  be  agitated 
as  little  as  possible  in  contact  with  the  air,  in  order  to 
avoid  the  absorption  of  oxygen.  A  siphon  should  be 
used  for  this  purpose,  the  lower  end  being  allowed  to  reach 
to  the  bottom  of  the  bulb. 

The  following  modification  is  suggested  as  being  especi- 
ally suitable  for  poorly  oxygenated  waters :  An  accurately 
stoppered  bottle,  the  exact  capacity  of  which  is  known 
(about  500  c.  c.  is  a  convenient  size),  is  completely  filled 
at  the  source  with  the  water  to  be  examined,  and  the  stop- 
per inserted  so  as  to  drive  out  all  air.  The  stopper  is  re- 
moved in  the  laboratory,  50  c.  c.  of  the  water  drawn  off 
with  a  pipette,  and  the  water  covered  immediately  with  a 
layer  of  gasoline  previously  purified  by  shaking  up  several 
times  with  a  solution  of  potassium  permanganate  and 
diluted  sulphuric  acid,  and  washed  several  times  with  water. 


SANITARY    EXAMINATIONS.  47 

The  sodium  hydroxide,  ferrous-ammonium  sulphate  and 
sulphuric  acid  are  introduced  into  the  water  by  means  of 
burettes  to  which  long  glass  delivery  tubes  are  attached. 
The  titration  with  potassium  permanganate  is  conducted 
in  the  same  way.  The  liquid  is  mixed  from  time  to  time, 
as  the  solutions  are  added,  by  means  of  a  glass  rod.  In 
this  way  the  air  may  be  completely  excluded  throughout 
the  entire  operation.  The  amount  of  water  titrated  is,  of 
course,  equal  to  the  whole  capacity  of  the  bottle,  less  the 
50  c.  c.  removed  by  the  pipette. 

The  control  experiment  on  an  equal  volume  of  the  water, 
and  the  correction  for  the  oxygen  added  with  the  sodium 
hydroxide  solution,  are  made  as  detailed  above. 

Dupre  has  employed  the  determination  of  free  oxygen 
for  the  estimation  of  the  proportion  of  oxygen-consuming 
microbes.  The  principle  of  the  method  is  that  pure  water, 
if  kept  in  a  closed  bottle,  will  neither  gain  nor  lose  oxygen 
in  any  length  of  time,  but  if  organisms  capable  of  causing 
absorption  of  oxygen  are  present,  the  quantity  will  de- 
crease. 

The  experiment  is  carried  out  by  placing  a  sample  of 
the  water  in  a  clean  bottle,  and  vigorously  shaking  it  to 
saturate  with  air.  A  clean  250  c.  c.  bottle  is  completely 
filled  with  the  water,  tightly  stoppered,  and  maintained  at 
a  temperature  of  68°  F.  for  ten  days ;  the  free  oxygen  re- 
maining is  then  determined. 

POISONOUS  METALS. 

In  this  class  are  included  barium,  chromium,  zinc,  arsenic, 
copper  and  lead;  manganese  and  iron  also,  though  not  usually 
classed  in  this  group,  are  objectionable  when  present  in 
notable  amounts. 


48  ANALYTICAL    OPERATIONS. 

Barium  is  rarely  present,  and  only  in  water  containing 
no  sulphates.  It  can  be  detected  and  estimated  by  slightly 
acidifying  the  water  with  hydrochloric  acid,  filtering  if 
necessary,  and  adding  solution  of  calcium  sulphate.  The 
precipitated  barium  sulphate  is  collected  and  weighed  in 
the  usual  way. 

Chromium  is  rarely  present,  but  may  be  looked  for  in 
the  waste  waters  of  dye  works  and  similar  sources.  To 
detect  it,  a  considerable  volume  of  the  water  is  evaporated 
to  dryness  with  addition  of  a  small  amount  of  potassium 
chlorate  and  nitrate,  transferred  to  a  porcelain  crucible  and 
brought  to  quiet  fusion  ;  any  chromium  present  will  be 
found  in  the  residue  in  the  form  of  chromate.  The  fused 
mass,  after  cooling,  is  boiled  with  a  little  water,  filtered, 
the  filtrate  rendered  slightly  acid  with  hydrochloric 
acid,  and  a  solution  of  hydrogen  dioxide  added.  In  the 
presence  of  chromium  a  transient  blue  color  will  appear ; 
by  adding  a  little  ether,  and  shaking  the  mixture  the  color 
will  pass  into  the  ether,  and  on  standing  will  form  a  blue 
layer  on  the  surface  of  the  water. 

Zinc  is  best  detected  by  the  test  described  by  Allen. 
The  water  is  rendered  slightly  ammoniacal,  heated  to  boil- 
ing, filtered,  and  the  clear  liquid  treated  with  a  few  drops 
of  potassium  ferrocyanide;  in  the  presence  even  of  the 
merest  trace  of  zinc  a  white  precipitate  will  be  produced. 

Arsenic  is  most  readily  detected  by  Reinsch's  test.  One 
liter  of  the  water  is  rendered  slightly  alkaline  by  sodium 
carbonate,  free  from  arsenic,  and  evaporated  nearly  to  dry- 
ness  in  a  porcelain  basin.  2  or  3  c.  c.  of  water  strongly 
acidulated  with  hydrochloric  acid  are  placed  in  a  small 
test-tube,  about  y^  square  centimeter  of  bright  copper 
foil  is  added,  and  the  liquid  boiled  gently  for  a  few 


SANITARY    EXAMINATIONS.  49 

moments.  If  the  copper  remains  bright,  showing  that  the 
reagents  contain  no  arsenic,  the  water-residue  is  acidified 
with  hydrochloric  acid,  added  to  the  contents  of  the  test- 
tube,  and  the  liquid  again  boiled  for  several  minutes.  If 
arsenic  be  present,  a  steel-gray  stain  will  appear  on  the 
copper.  The  slip  is  removed,  washed  with  distilled  water, 
thoroughly  dried  by  pressure  between  filter  paper,  inserted 
into  a  narrow  glass  tube  closed  at  one  end,  which  has  been 
previously  dried  by  heating  nearly  to  redness.  The  tube  is 
gently  heated  at  the  point  at  which  the  copper  rests ;  the 
arsenical  deposit  will  sublime  and  collect  on  the  cooler 
portion  of  the  tube,  in  crystals  which  the  microscope  shows 
to  be  octahedral. 

Since  small  amounts  of  arsenic  frequently  occur  in 
reagents  and  in  glass  vessels,  care  must  be  taken  to  avoid 
such  sources  of  error.  Sodium  carbonate  solution  may 
contain  arsenic  dissolved  from  the  glass  bottle  in  which  it 
is  kept.  It  is  best,  therefore,  to  use  the  solid  carbonate  for 
rendering  the  water  alkaline,  and  to  determine  its  freedom 
from  arsenic  before  use. 

Iron  is  detected  by  the  addition  of  a  drop  of  ammonium 
sulphide  to  the  water  in  a  tall  glass  cylinder.  Ferrous  sul- 
phide is  formed,  having  a  greenish-black  color,  instantly 
discharged  by  acidifying  the  water  with  dilute  hydrochloric 
acid.  A  still  better  test  is  the  production  of  a  blood-red 
color,  with  potassium  sulphocyanate,  due  to  the  formation 
of  ferric  sulphocyanate.  The  water  should  be  first  boiled 
with  a  few  drops  of  nitric  acid,  to  convert  the  iron  to  the 
ferric  condition,  cooled,  and  a  drop  or  two  of  the  solution 
of  potassium  sulphocyanate  added.  The  test  is  very  deli- 
cate. Either  of  the  above  tests  may  be  made  quantitative 


50  ANALYTICAL  OPERATIONS. 

by  matching  the  color  produced  in  100  c.  c.  of  the  water 
with  that  obtained  from  a  known  weight  of  iron.  The 
method  with  potassium  sulphocyanate  is  preferable,  as  it  is 
more  delicate  and  there  are  fewer  interfering  conditions. 
The  following  is  the  method  as  elaborated  by  Thompson 
and  described  in  Button's  "Volumetric  Analysis:  " — 
Solutions  Required : — 

Standard  Ferric  Sulphate. — 0.7  gram  ferrous  ammonium 
sulphate  are  dissolved  in  water  acidified  with  sulphuric 
acid,  and  potassium  permanganate  solution  added  until  the 
solution  turns  a  very  faint  pink  color.  The  solution  is 
diluted  to  a  liter,  i  c.  c.  contains  o.i  milligram  iron. 

Diluted  Nitric  Acid. — 30  c.  c.  concentrated  nitric  acid 
diluted  with  water  to  about  100  c.  c. 

Potassium  Sulphocyanate. — 5  grams  of  the  salt  dissolved 
in  about  100  c.  c.  water. 
Analytical  Process : — 

About  100  c.  c.  of  the  water  are  evaporated  to  small  bulk, 
acidified  with  hydrochloric  acid,  and  just  sufficient  dilute 
potassium  permanganate  solution  added  to  convert  all  the 
iron  to  the  ferric  condition.  The  liquid  is  evaporated 
nearly  to  dryness  to  drive  off  excess  of  acid,  then  diluted 
to  its  original  volume,  100  c.  c.  In  two  tall  glasses 
marked  at  100  c.  c.,  5  c.  c.  of  the  nitric  acid  and  fifteen 
c.  c.  of  the  sulphocyanate  solution  are  placed.  To  one  of 
these  a  measured  volume  of  the  treated  water  is  added  and 
both  vessels  filled  up  to  the  mark  with  distilled  water.  If 
iron  is  present,  a  blood-red  color  will  be  produced.  Stand- 
ard iron  solution  is  added  to  the  second  vessel  until  the  color 
agrees.  The  amount  of  water  which  is  added  to  the  first 
glass  will  depend  upon  the  quantity  of  iron  it  contains ; 


SANITARY    EXAMINATIONS.  51 

not  more  should  be  used  than  will  require  two  or  three  c.  c. 
of  the  standard  to  match  it,  otherwise  the  color  will  be  too 
deep  for  comparison. 

Manganese. — The  following  method  is  described  by 
Wanklyn  in  his  treatise  on  water  analysis.  About  one  liter 
of  the  water  is  evaporated  to  small  bulk,  nearly  neutralized 
by  hydrochloric  acid  and  treated  with  a  few  drops  of  a 
solution  of  hydrogen  dioxide.  The  formation  of  a  brown 
precipitate  indicates  the  presence  of  manganese.  The  test 
is  very  delicate.  The  precipitate  may  be  collected  on 
a  filter,  the  filter  ashed,  and  the  residue  fused  with  a  mix- 
ture of  sodium  carbonate  and  potassium  nitrate.  Green 
potassium  manganate  will  be  produced,  which,  when  boiled 
with  water,  will  give  a  bright  red  solution  of  potassium 
permanganate.  The  quantitative  determination  is  given 
elsewhere. 

Lead  may  be  readily  detected  by  adding  to  the  water  in 
a  tall  glass  cylinder  a  drop  of  ammonium  sulphide  ;  brown- 
ish black  lead  sulphide  is  formed,  which  does  not  dissolve 
either  by  acidulating  the  water  with  dilute  hydrochloric 
acid  (distinction  from  iron)  nor  by  the  addition  of  about 
one  c.  c.  of  a  strong  solution  of  potassium  cyanide  (dis- 
tinction from  copper).  S.  Harvey  {Analyst,  April,  1890} 
gives  the  following  method  for  detecting  lead  in  water : 
250  c.  c.  are  placed  in  a  conical  precipitating  jar,  about 
o.  i  gram  of  crystallized  potassium  dichromate  is  added 
and  dissolved  by  agitation.  The  same  volume  of  lead-free 
water  is  treated  in  the  same  manner,  and  the  two  solutions 
placed  side  by  side.  Water  containing  0.3  parts  per  mil- 
lion, will  show  a  turbidity  in  fifteen  minutes,  which  will  be 
rendered  more  distinct  by  contrast  with  the  clear  water 
alongside.  By  allowing  the  jar  to  stand  for  about  twelve 


52  ANALYTICAL    OPERATIONS. 

hours  undisturbed,  the  precipitate  will  settle  and  will  be- 
come still  more  distinct.  No  other  metal  likely  to  be  pres- 
ent in  water  will  give  a  similar  reaction. 

In  the  absence  of  copper,  the  amount  of  lead  present 
may  be  determined  as  follows :  A  solution  is  prepared  con- 
taining 1.6  grams  of  lead  nitrate  to  the  liter;  one  c.  c.  of 
this  contains  one  milligram  lead.  100  c.  c.  of  the  water  to 
be  tested  are  placed  in  a  tall  glass  vessel,  made  acid  by  the 
addition  of  a  few  drops  of  acetic  acid  and  five  c.  c.  of 
hydrogen  sulphide  added.  In  a  similar  vessel  100  c.  c.  of 
distilled  water  are  placed,  together  with  the  same  quantities 
of  acetic  acid  and  hydrogen  sulphide,  and  sufficient  of  the 
standard  lead  solution  to  match  the  tint  in  the  first  cylinder. 
The  amount  of  lead  in  the  water  under  examination  is  thus 
known. 

Copper  is  detected  in  the  same  manner  as  lead  by 
acidifying  the  water  with  acetic  acid  and  adding  hydrogen 
sulphide  water.  The  precipitate  is  distinguished  from  lead 
sulphide  by  the  fact  that  the  color  is  discharged  on  the 
addition  of  about  one  c.  c.  of  a  strong  solution  of  pure 
potassium  cyanide.  It  may  be  further  confirmed  by  the 
addition  to  another  portion  of  the  water  of  a  solution  of 
potassium  ferrocyanide.  In  the  presence  of  even  a  very 
small  amount  of  copper,  a  mahogany  red  color  is  produced. 

In  the  absence  of  lead,  copper  is  estimated  in  the  same 
way  as  that  metal,  using,  however,  a  standard  solution  of 
copper  for  the  comparison  liquid.  This  is  made  by  dis- 
solving 3.929  grams  of  crystallized  copper  sulphate  in  one 
liter  of  water.  One  c.  c.  of  the  solution  contains  one 
milligram  copper. 

If  both  lead  and  copper  are  present,  a  large  quantity  of 
the  water  should  be  evaporated  to  small  bulk,  and  the 


TECHNICAL    EXAMINATIONS. 


53 


metals  separated  and  estimated  by  any  one  of  the  ordinary 
laboratory  methods. 

The  following  table,  prepared  by  A.  J.  Cooper,  indicates 
the  comparative  delicacy  of  some  of  the  ordinary  tests  for 
the  detection  of  poisonous  metals  in  water  : — 


Metal. 

Reagent. 

Depth  of  Liquid,  3^  inches. 

Depth  of  Liquid,  14^  inches. 
Cylinder  enclosed  in  opaque 

tube. 

i  part  of  metal  detected  in 

i  part  of  metal  detected  in 

Copper  .   .   . 

K4Cy6Fe 
NH4HO 

4,000,000  of  water. 
1,000,000 

11,750,000  of  water. 
1,950,000         ' 

" 

H2S 

4,150,000 

15,660,000         ' 

Zinc  .... 

NH4HS 

2,500,000 

Arsenic    .    . 

KH'°S 

3,600,000 

7,520,000 

Lead  .... 

4,000,000 

5,875,000 

.  .  .    . 

fe2s4 

100,000,000 

196,000,000         ' 

TECHNICAL  EXAMINATIONS. 

GENERAL  QUANTITATIVE  ANALYSIS. 

Silica,  Iron,  Aluminum,  Manganese,  Calcium, 
and  Magnesium. — One  liter  of  the  water  acidified  with 
hydrochloric  acid  is  evaporated  to  complete  dryness,  best 
in  a  platinum  dish,  the  residue  treated  with  hydrochloric 
acid  and  water,  and  the  separated  silica  filtered,  washed, 
dried,  ignited  in  a  platinum  crucible  and  weighed. 

To  the  filtrate,  previously  boiled  with  a  few  drops  of 
strong  nitric  acid,  slight  excess  of  ammonium  hydroxide  is 
added,  the  liquid  boiled  several  minutes,  the  precipitate 
collected,  washed  thoroughly  with  boiling  water,  dried, 
ignited  and  weighed.  It  consists  of  Fc^O*  and  Al^O^.  It 
also  contains  all  the  phosphates  and  some  manganese  if 
much  is  present  in  the  water.  In  such  cases  the  precipitate 


54  ANALYTICAL  OPERATIONS. 

before  drying  is  re-dissolved  in  hydrochloric  acid  and 
neutralized  with  a  dilute  solution  of  ammonium  carbonate 
until  the  water  almost  becomes  turbid.  It  is  then  boiled 
and  the  precipitate,  now  free  from  manganese,  washed, 
dried,  ignited  and  weighed.  The  iron  may  be  determined 
by  dissolving  the  precipitate  in  strong  hydrochloric  acid 
and  employing  the  colorimetric  method  described  on  page 

5°- 

If  no  manganese  or  only  traces  are  present,  the  filtrate 
from  the  iron  is  mixed  with  sufficient  ammonium  chloride 
to  prevent  the  precipitation  of  the  magnesium,  ammonium 
hydroxide,  and  then  ammonium  oxalate  added  in  quantity 
sufficient  to  precipitate  the  calcium  and  to  convert  all  the 
magnesium  into  oxalate,  and  thus  hold  it  in  solution.  The 
precipitate  contains  all  the  calcium  and  some  of  the  mag- 
nesium. If  the  magnesium  is  present  only  in  relatively  small 
quantity  the  amount  carried  down  may  be  disregarded  ; 
otherwise  a  second  precipitation  should  be  made  as  follows : 
The  solution  is  allowed  to  stand  until  the  precipitate  has 
subsided ;  this  will  require  some  hours.  The  supernatant 
liquid  is  poured  off  through  a  filter,  the  precipitate  washed 
by  decantation,  then  dissolved  in  hydrochloric  acid,  water 
added,  then  ammonium  hydroxide  and  a  small  quantity 
of  ammonium  oxalate.  After  the  calcium  oxalate  has 
thoroughly  subsided  it  is  filtered  off,  washed  and  dried.  If 
quite  small  in  amount  it  is  placed  with  the  filter  in  a  weighed 
platinum  crucible,  ignited  over  the  Bunsen  burner  for  a 
short  time,  and  then  over  the  blast  lamp  for  from  five  to 
fifteen  minutes.  The  calcium  is  thus  obtained  in  the  form 
of  oxide,  which  is  allowed  to  cool  in  the  desiccator  and 
weighed.  The  weight  thus  obtained  multiplied  by  0.7142 
gives  the  weight  of  calcium.  When  the  amount  of  precipi- 


TECHNICAL    EXAMINATIONS.  55 

tate  is  large,  it  is  better  to  remove  it  from  the  filter,  and 
heat  it  just  short  of  redness  until  it  assumes  a  grayish  tint. 
It  then  consists  of  calcium  carbonate.  To  this  is  added 
the  ash  of  the  filter.  The  weight  of  the  calcium  carbonate 
multiplied  by  0.4  gives  the  weight  of  calcium. 

The  filtrates  are  mixed,  slightly  acidified  with  hydro- 
chloric acid,  concentrated  and  cooled,  ammonium  hydrox- 
ide and  sodium  phosphate  added  in  excess,  stirred  briskly 
and  allowed  to  stand  in  the  cold  for  about  twelve  hours. 
The  precipitated  ammonium  magnesium  phosphate  is 
brought  upon  a  filter,  that  adhering  to  the  sides  of  the  ves- 
sel being  dislodged  by  rubbing  with  a  glass  rod  tipped  with 
a  piece  of  clean  rubber  tubing.  It  is  washed  with  a  solu- 
tion made  by  mixing  one  part  of  the  ammonium  hydroxide 
of  0.96  sp.  gr.  with  three  parts  of  water.  The  precipitate  is 
dried,  transferred  to  a  platinum  crucible,  the  filter  ashed 
separately  and  added  to  it,  and  the  whole  heated  at  first 
gently  and  then  to  intense  redness  for  several  minutes. 
After  cooling,  it  is  weighed.  It  consists  of  magnesium 
pyrophosphate  ;  the  weight  multiplied  by  0.2162  gives  the 
weight  of  magnesium. 

Manganese,  if  present  in  appreciable  quantity,  is  sepa- 
rated before  the  precipitation  of  the  calcium,  as  follows : 
The  filtrate  from  the  iron  precipitate  is  slightly  acidulated 
with  hydrochloric  acid,  concentrated,  and  the  manganese 
precipitated  as  sulphide  by  colorless  or  slightly  yellow  solu- 
tion of  ammonium  sulphide.  The  flask,  which  should  be 
nearly  full,  is  stoppered,  allowed  to  rest  in  a  moderately 
warm  place  until  the  precipitate  has  thoroughly  settled, 
filtered,  washed  with  dilute  ammonium  sulphide  water  and 
purified  by  dissolving  in  a  small  quantity  of  hydrochloric 
acid  and  reprecipitating  with  ammonium  sulphide.  It  is 


56  ANALYTICAL   OPERATIONS. 

filtered  off,  washed  as  before,  dried,  placed  in  a  weighed 
porcelain  crucible,  covered  with  a  little  sulphur  and  ignited 
in  a  current  of  hydrogen  introduced  into  the  crucible  by  a 
tube  passing  through  a  hole  in  the  cover.  The  pure  man- 
ganese sulphide  thus  obtained  is  allowed  to  cool  and 
weighed.  The  weight  multiplied  by  .63218  gives  mangan- 
ese. 

Sulphates. — 500  c.  c.  of  the  clear  water  are  slightly 
acidulated  with  hydrochloric  acid,  heated  to  boiling,  and 
barium  chloride  solution  added  in  moderate  excess.  The 
precipitate  is  allowed  to  subside  completely,  collected  upon 
a  filter,  washed  thoroughly,  dried  and  incinerated.  It  is 
BaSO4;  the  weight  multiplied  by  0.412  gives  SO4.  If  the 
proportion  of  SO4  is  very  low,  it  will  be  advisable  to  con- 
centrate the  water  to  one-fifth  or  one-tenth  its  bulk  before 
precipitating. 

Control.  Potassium,  Sodium  and  Lithium. — 
From  250  to  TOGO  c.  c.  of  the  water,  according  to  the 
amount  of  solid  matters  present,  are  evaporated  to  dryness 
in  a  platinum  dish,  and  the  residue  heated  in  an  air-bath 
to  about  360°  F.,  until  the  weight  becomes  constant.  This 
determines  the  total  solid  matter  in  solution. 

The  residue  is  treated  with  a  small  amount  of  water  and 
sufficient  dilute  sulphuric  acid  to  decompose  the  salts  pres- 
ent. The  dish  should  then  be  covered  and  placed  upon  the 
water-bath  for  five  or  ten  minutes,  after  which  any  liquid 
spurted  on  the  cover  is  washed  into  the  dish,  the  whole 
evaporated  to  dryness  and  heated  to  redness.  A  few  drops 
of  ammonium  carbonate  solution  should  then  be  mixed  with 
the  residue,  and  the  ignition  repeated  to  insure  the  removal 
of  the  last  portions  of  free  acid.  In  the  majority  of  cases 
the  only  basic  elements  present  in  considerable  quantity 


TECHNICAL    EXAMINATIONS.  57 

are  calcium,  magnesium  and  sodium.  The  sodium  may  be 
determined  indirectly,  therefore,  by  calculating  from  the 
amount  of  Ca  and  Mg  found,  the  calcium  and  magne- 
sium sulphate  in  the  residue,  and  subtracting  this  sum, 
together  with  the  silica,  from  the  total  residue. 

If  potassium  or  potassium  and  lithium,  also,  are  to  be 
estimated,  the  filtrate  from  the  precipitation  of  the  SO4 
may  be  used,  provided  that  sufficient  of  the  water  has  been 
used  for  the  estimation.  For  the  determination  of  potas- 
sium and  sodium  in  ordinary  well  and  river  waters,  not  less 
than  one  liter  should  be  employed.  When  lithium  is  to  be 
determined,  it  is  generally  necessary  to  use  at  least  two  or 
three  liters.  In  any  case,  as  the  alkalies  are  to  be  weighed 
as  chlorides,  it  is  advisable  to  precipitate  the  sulphates  by 
addition  of  barium  chloride.  Unless  the  sulphates  are  to 
be  estimated  in  this  portion,  it  is  unnecessary  to  remove 
the  precipitate  of  barium  sulphate  so  formed. 

The  water  is  evaporated  to  about  200  c.  c.,  thin,  pure 
milk  of  lime  added  in  slight  excess — generally  from  two  to 
three  c.  c.  will  be  sufficient — to  the  hot  liquid,  and  the  heat 
continued  for  several  minutes.  It  is  then  washed  into  a  250 
c.  c.  flask,  disregarding  the  insoluble  portion  adhering  to 
the  dish,  which,  however,  should  be  thoroughly  washed, 
and  the  washings  added  to  the  flask.  After  cooling,  the 
flask  is  filled  up  to  the  mark  with  distilled  water,  thoroughly 
mixed,  the  precipitate  allowed  to  settle,  and  the  liquid 
filtered  through  a  dry  filter.  200  c.  c.  of  the  filtrate  are 
measured  into  another  250  c.  c.  flask,  ammonium  carbonate 
and  ammonium  oxalate  added,  filled  with  water  up  to  the 
mark, .mixed,  allowed  to  settle,  filtered  through  a  dry  filter, 
200  c.  c.  of  the  filtrate  measured  off  and  evaporated  to 
thorough  dryness  in  a  platinum  crucible,  heating  very 
E 


58  ANALYTICAL  OPERATIONS. 

cautiously  at  the  last  stages  to  avoid  loss  by  spurting.  The 
low-temperature  burner  is  suited  for  this  purpose.  The 
crucible  is  now  covered  and  cautiously  heated  to  dull 
redness,  cooled  and  weighed.  The  residue  consists  of 
potassium,  lithium  and  sodium  chlorides.  It  contains 
sometimes,  also,  traces  of  magnesium,  which  may  be  re- 
moved by  treating  again  with  lime  and  with  ammonium 
carbonate  and  oxalate.  It  is  frequently  of  advantage,  in 
evaporating  these  saline  solutions,  to  add,  when  the  solu- 
tion becomes  concentrated,  several  c.  c.  of  strong  hydro- 
chloric acid.  This  precipitates  the  greater  portion  of  the 
salts  in  a  finely  granular  condition,  and  renders  loss  by 
spurting  less  liable  to  occur. 

If  potassium  and  sodium  chlorides  only  are  present,  they 
can  be  readily  estimated  by  dissolving  the  weighed  residue 
in  water,  determining  the  total  chlorine  by  titration  with 
silver  nitrate  and  potassium  chromate,  and  applying  the  fol- 
lowing rule  :  "  Multiply  the  quantity  of  chlorine  in  the 
mixture  by  2.1035,  deduct  from  the  product  the  sum  of  the 
chlorides,  and  multiply  the  remainder  by  3.6358  ;  the  pro- 
duct expresses  the  quantity  of  sodium  chloride  contained 
in  the  mixed  chloride." 

The  results  by  this  method  are  not  accurate  if  either 
the  potassium  or  the  sodium  is  present  in  relatively  small 
amount.  In  such  cases  the  following  procedure  may  be 
resorted  to.  The  weighed  chlorides  are  dissolved  in  a  small 
quantity  of  water,  an  excess  of  a  concentrated  neutral  solu- 
tion of  platinum  chloride  added,  evaporated  nearly  to  dry- 
ness  at  a  low  heat  on  the  water  bath,  some  80  per  cent, 
alcohol  added,  allowed  to  stand,  the  clear  liquor  decanted 
off  on  a  small  filter  and  the  residue  washed  in  this  way  sev- 
eral times  by  fresh  small  portions  of  80  per  cent,  alcohol. 


TECHNICAL    EXAMINATIONS.  59 

The  precipitate  is  then  washed  on  to  the  filter  with  alcohol, 
washed  again  with  80  per  cent,  alcohol,  thoroughly  dried 
and  transferred  as  far  as  possible  to  a  watch  glass.  The 
small  portion  on  the  filter  is  dissolved  off  and  the  solution 
placed  in  a  weighed  platinum  dish  and  evaporated  to  dry- 
ness.  The  main  portion  on  the  watch  glass  is  then  added, 
and  the  whole  dried  to  a  constant  weight  at  about  260°  F., 
cooled  and  weighed.  The  weight  thus  found  multiplied  by 
.30557  gives  the  weight  of  potassium  chloride.  This  sub- 
tracted from  the  combined  weight  of  the  chlorides  gives 
the  weight  of  sodium  chloride. 

Lithium,  if  present,  is  best  separated  before  the  treatment 
with  platinum  chloride.  The  following  method,  devised 
by  Gooch,  gives  good  results  :  To  the  concentrated  solu- 
tion of  the  weighed  chlorides,  amyl  alcohol  is  added  and 
heat  applied,  gently  at  first,  to  avoid  bumping,  until  the 
water  disappears  from  the  solution  and  the  point  of  ebulli- 
tion becomes  constant  at  a  temperature  which  is  approxi- 
mately that  at  which  the  alcohol  boils  (270°  F.),  the 
potassium  and  sodium  chlorides  are  deposited  and  the 
lithium  chloride  is  dehydrated  and  taken  into  solution. 
The  liquid  is  then  cooled  and  a  drop  or  two  of  strong 
hydrochloric  acid  added  to  reconvert  traces  of  lithium  hy- 
droxide in  the  deposit,  and  the  boiling  continued  until  the 
alcohol  is  again  free  from  water.  If  the  amount  of  lithium 
chloride  be  small,  it  will  be  found  in  the  solution  and  the 
potassium  chloride  and  sodium  chloride  in  the  residue, 
excepting  traces  which  can  be  allowed  for.  If  the  lithium 
chloride  exceed  ten  or  twenty  milligrams  the  liquid  may  be 
decanted,  the  residue  washed  with  amyl  alcohol,  dissolved 
in  a  few  drops  of  water  and  treated  as  before.  For  wash- 
ing, amyl  alcohol  previously  dehydrated  by  boiling  is  to  be 


60  ANALYTICAL    OPERATIONS. 

used,  and  the  filtrates  are  to  be  measured  apart  from  the 
washings.  In  filtering,  the  Gooch  filter  with  asbestos  felt 
may  be  used  with  advantage,  applying  gentle  pressure  by 
the  aid  of  the  filter  pump.  The  crucible  and  residue  are 
ready  for  weighing  after  gentle  heating  over  the  low-tem- 
perature burner.  The  weight  of  the  insoluble  chlorides  is 
to  be  corrected  by  adding  .00041  for  every  ten  c.  c.  of  amyl 
alcohol  in  the  filtrate,  exclusive  of  the  washings,  if  only 
sodium  chloride  be  present;  .00051  for  every  ten  c.  c.  if 
only  potassium  chloride,  and  .00092  in  the  presence  of 
both  these  chlorides. 

The  filtrate  and  washings  are  evaporated  to  dryness  in  a 
platinum  crucible  heated  with  sulphuric  acid,  the  excess 
driven  off,  and  the  residue  ignited  to  fusion,  cooled  and 
weighed.  From  the  weight  is  to  be  subtracted,  for  each  ten 
c.  c.  of  filtrate,  .0005,  .00059,  or  .00109,  according  as  only 
sodium  chloride,  potassium  chloride,  or  both  were  present 
in  the  original  mixture. 

Hydrogen  Sulphide. — The  following  method  is  taken 
from  Button's  "  Volumetric  Analysis  :  " — 
Reagents  Required : — 

Centinormal  Iodine. — Dry,,  commercial  iodine  is  inti- 
mately mixed  with  one-fourth  its  weight  of  pure  potassium 
iodide  and  gently  heated  between  two  clock-glasses  by 
resting  the  lower  on  a  hot  plate.  The  iodine  sublimes  in  a 
perfectly  pure  condition.  It  is  allowed  to  cool  under  the 
desiccator,  1.265  grams  weighed  out,  together  with  1.8 
grams  of  pure  potassium  iodide,  dissolved  in  about  50  c.  c. 
of  water  and  the  solution  made  up  exactly  to  a  liter.  The 
liquid  must  not  be  heated,  and  care  should  be  taken  that 
no  iodine  vapor  is  lost.  One  c.  c.  is  equivalent  to  .00017 
H2S.  The  solution  is  best  preserved  in  stoppered  bottles, 


TECHNICAL    EXAMINATIONS.  6 1 

which  should  be  completely  filled  and  kept  in  the  dark. 
It  will  not  even  then  keep  very  long,  and  should  be  standard- 
ized by  titration  with  a  weighed  amount  of  pure  sodium 
thiosulphate,  which  should  be  powdered  previous  to  weigh- 
ing, and  pressed  between  filter  paper  to  absorb  any  mois- 
ture. 50  c.  c.  of  the  iodine  solution,  when  of  full  strength, 
will  require  0.124  gram  of  sodium  thiosulphate. 

Starch  Indicator. — See  page  39. 
Analytical  Process : — 

10  c.  c.,  or  any  other  necessary  volume  of  the  iodine 
solution,  is  measured  into  a  500  c.  c.  flask,  and  the  water 
to  be  examined  added  until  the  color  disappears.  5  c.  c. 
of  starch  liquor  are  then  added  and  the  iodine  solution  run 
in  until  the  blue  color  appears ;  the  flask  is  then  filled  to 
the  mark  with  distilled  water.  The  respective  volumes  of 
iodine  and  starch  solution,  together  with  the  added  water, 
deducted  from  the  500  c.  c.  will  show  the  volume  of  water 
actually  titrated  by  iodine.  A  correction  should  be  made 
as  follows  for  the  excess  of  iodine  required  to  produce  the 
blue  color :  5  c.  c.  starch  solution  are  made  up  with  dis- 
tilled water  to  500  c.  c.,  iodine  run  in  until  the  color 
matches  that  in  the  test,  and  the  volume  of  iodine  solution 
so  used  subtracted  from  the  figure  obtained  in  the  first 
titration. 

Hardness.  CO3  in  Normal  Carbonates. — Waters 
containing  considerable  quantities  of  calcium  and  magne- 
sium salts  are  said  to  be  hard.  Since  the  solution  of  cal- 
cium and  magnesium  carbonate  in  water  depends  partly  upon 
the  presence  of  carbon  dioxide,  boiling  precipitates  the 
greater  portion  of  the  carbonates,  the  result  being  to  diminish 
the  hardness,  i.  e.,  soften  the  water.  Magnesium  and  cal- 
cium sulphates  and  chlorides  are  not  precipitated  in  this 


62  ANALYTICAL    OPERATIONS. 

way.     Hardness,    therefore,  is   divided   into  two   classes, 
temporary  and  permanent,  the   former  being  that  which 
may  be  removed  by  boiling.     The  process  here  described 
is  due  to  Hehner. 
Reagents  Required  :— 

Standard  Sodium  Carbonate. — 1.06  grams  of  recently 
ignited  pure  sodium  carbonate  are  dissolved  in  water  and 
the  solution  diluted  to  1000  c.  c.  i  c.  c.  =.00106  gram 
Na2CO3,  equivalent  to  .001  gram  CaCO3. 

Standard  Sulphuric  Acid. — i  c.  c.  of  pure  concentrated 
sulphuric  acid  is  added  to  about  1000  c.  c.  of  water.  50  c.  c. 
of  the  standard  sodium  carbonate  are  placed  in  a  porce- 
lain dish,  heated  to  boiling,  a  few  drops  of  a  solution  of 
phenacetolin  or  lacmoid  added,  and  the  sulphuric  acid 
cautiously  run  in  from  a  burette  until  the  proper  change  of 
color  occurs.  From  the  figure  thus  obtained,  the  extent 
to  which  the  acid  should  be  diluted  in  order  to  make  i  c.  c. 
of  the  sodium  carbonate  equivalent  to  i  c.  c.  of  the  acid  may 
be  calculated.  The  proper  amount  of  water  is  then  added 
and  the  solution  verified  by  again  titrating. 
Analytical  Process : — 

Temporary  Hardness. — 100  c.  c.  to  250  c.  c.  of  the  water 
tinted  with  the  indicator  are  heated  to  boiling,  and  the  sul- 
phuric acid  cautiously  run  in  until  the  color  change  occurs. 
Each  c.  c.  required  will  represent  one  part  of  calcium  car- 
bonate or  its  equivalent  per  100,000  parts  of  the  water. 

Permanent  Hardness. — To  100  c.  c.  of  the  water  is 
added  an  amount  of  the  sodium  carbonate  solution  more 
than  sufficient  to  decompose  the  calcium  and  magnesium 
sulphates,  chlorides  and  nitrates  present;  usually  a  bulk 
equal  to  the  water  taken  will  be  more  than  sufficient.  The 
mixture  is  evaporated  to  dryness  in  a  nickel  or  platinum 


TECHNICAL    EXAMINATIONS.  63 

dish,  and  the  residue  extracted  with  distilled  water.  The 
solution  is  filtered  through  a  very  small  filter,  and  the  filtrate 
and  washings  titrated  hot  with  sulphuric  acid  as  above ;  or 
25  c.  c.  of  distilled  water  may  be  poured  on  the  residue, 
and  the  solution  obtained  filtered  through  a  dry  filter,  the 
filtrate  measured  and  titrated.  The  difference  between 
the  number  of  c.  c.  of  sodium  carbonate  used  and  the 
acid  required  for  the  residue  will  give  the  permanent 
hardness. 

If  the  water  contains  sodium  or  potassium  carbonate 
there  will  be  no  permanent  hardness,  and  there  will  be 
more  acid  required  for  the  filtrate  than  the  equivalent  of 
the  sodium  carbonate  added.  From  this  excess  the 
quantity  of  sodium  carbonate  in  the  water  may  be  deter- 
mined. 

Since  any  alkali  carbonate  in  the  water  would  be  erro- 
neously calculated  as  temporary  hardness  by  the  direct 
titration,  the  equivalent,  in  terms  of  calcium  carbonate,  of 
the  alkali  carbonate  present  should  be  deducted  from  the 
figure  given  by  the  titration  in  order  to  get  the  true  tempo- 
rary hardness. 

The  total  CO3  in  normal  carbonates  is  given  by  the  direct 
titration  of  the  water  with  dilute  sulphuric  acid.  One  c.  c. 
of  the  acid  is  equivalent  to  .0006  gram  of  CO3. 

Free  Carbonic  Acid. — The  following  process,  due  to 
Pettenkofer,  is  taken  from  Button's  "Volumetric  Analy- 
sis":— 

A  stoppered  bottle  of  known  capacity,  about  150  c.  c., 
is  filled  at  the  source  by  submergence,  or,  if  taken  from  a 
faucet,  by  allowing  the  stream  to  run  in  with  full  force  for 
some  minutes,  the  nozzle  being  inserted  into  the  neck  of 
the  bottle.  50  c.  c.  of  the  water  are  then  quickly  removed 


64  ANALYTICAL    OPERATIONS. 

by  a  pipette,  and  the  following  solutions  immediately 
added  :  3  c.  c.  of  a  saturated  solution  of  calcium  chloride 
and  2  c.  c.  of  a  saturated  solution  of  ammonium  chloride; 
45  c.  c.  of  clear  calcium  hydroxide  solution  of  known 
strength  are  added,  the  flask  well  corked,  the  liquids  mixed, 
and  set  aside  for  at  least  twelve  hours,  to  allow  the  calcium 
carbonate  formed  to  settle  and  become  crystalline  and 
insoluble.  An  aliquot  part  (50  to  TOO  c.  c.)  of  the  clear 
liquid  is  then  drawn  off  and  titrated  with  decinormal  acid, 
using  phenacetolin  or  lacmoid  as  indicator,  and  from  the 
amount  required  the  entire  proportion  of  calcium  hydroxide 
unacted  upon  can  be  determined.  This  being  deducted 
from  the  amount  originally  added,  and  the  remainder 
multiplied  by  .0022,  will  give  the  weight  of  carbonic 
acid  in  the  water  in  excess  of  that  existing  as  normal 
carbonates. 

Boric  Acid. — Detection. — Add  to  one  liter  of  the  water 
sufficient  sodium  carbonate  to  render  it  distinctly  alkaline. 
Evaporate  to  dryness,  acidify  with  hydrochloric  acid, 
moisten  a  slip  of  turmeric  paper  with  the  liquid,  and  dry  it 
at  a  moderate  heat.  In  the  presence  of  boric  acid  the  paper 
will  assume  a  distinct  brown-red  tint. 

Estimation. — The  following  method  for  determining 
boric  acid  is  due  to  Gooch,  and  has  been  found  very 
satisfactory.  One  liter  or  more  of  the  water  is  rendered 
alkaline,  if  necessary,  by  sodium  carbonate  and  evapo- 
rated to  dryness.  The  residue  is  transferred  as  completely 
as  possible  by  the  aid  of  slight  excess  of  acetic  acid  to 
a  flask  attached  to  a  condensing  apparatus,  arranged  as 
in  Fig.  8.  About  i  gram  of  pure  quicklime  is  heated 
in  a  platinum  crucible  over  the  blast  lamp  for  from 
five  to  fifteen  minutes,  to  decompose  any  hydroxide  or 


TECHNICAL    EXAMINATIONS. 


FIG.  8. 


66  ANALYTICAL    OPERATIONS. 

carbonate,  allowed  to  cool  in  the  desiccator,  and  weighed. 
It  is  then  introduced  into  the  Erlenmeyer  flask,  slaked  by 
the  addition  of  a  few  c.  c.  of  water,  and  the  flask  attached 
to  the  lower  end  of  the  condenser,  as  shown  (Fig.  8).  The 
terminal  tube  of  the  condensing  apparatus  should  dip  into 
the  milk  of  lime.  The  hemispherical  copper  basin  contains 
paraffin,  which  is  heated  to  a  temperature  of  about  250°  F. 
The  bath  is  then  raised  so  as  to  immerse  the  entire  bulb  of 
the  flask,  and  the  liquid  distilled  to  dryness.  The  bath  is 
then  lowered,  and  when  the  flask  and  its  contents  have 
somewhat  cooled,  10  c.  c.  of  methyl  alcohol  are  introduced 
by  means  of  the  stoppered  funnel  tube,  the  bath  raised 
again,  and  the  liquid  again  distilled  to  dryness.  This 
manipulation  is  repeated  until  six  portions  of  10  c.  c.  of 
methyl  alcohol  have  been  distilled  off.  The  boric  acid 
will  distill  over  and  be  fixed  by  the  lime.  The  contents  of 
the  Erlenmyer  flask  are  concentrated  and  transferred  com- 
pletely to  the  same  crucible  in  which  the  lime  was  heated. 
Any  portions  adhering  to  the  sides  of  the  flask  or  to  the 
tube  may  be  dissolved  by  a  little  acetic  acid.  The  material 
in  the  crucible  is  cautiously  dried  and  heated  over  the  blast 
lamp  for  ten  minutes,  allowed  to  cool  in  the  desiccator 
and  weighed.  The  increase  in  weight  represents  boric 
anhydride, 


SPECTROSCOPIC   EXAMINATION. 

For  the  ordinary  spectroscopic  examination  of  a  water 
a  simple  apparatus  will  suffice.  The  arrangement  figured  in 
the  cut  (Fig.  9)  is  a  small  direct-vision  spectroscope,  held 
in  a  universal  stand,  with  Turquem's  adjustable  burner  as 
the  source  of  heat.  The  entire  apparatus  does  not  cost 
over  $15.00,  and  will  be  found  convenient  and  efficient. 


TECHNICAL    EXAMINATIONS. 


67 


FIG.  9. 


For  the  examination,  a  liter  or  more  should  be  evapo- 
rated nearly  to  dryness,  a  little  hydrochloric  acid  being 
added  near  the  end  of  the 
process,  the  residue  placed 
in  a  narrow  strip  of  plati- 
num foil  having  the  sides 
bent  so  as  to  retain  the 
liquid,  and  heated  in  the 
flame.  While  this  method 
will  be  sufficient  in  many 
cases,  a  far  better  plan  is 
to  separate  the  substance 
sought  for  in  a  state  of  ap- 
proximate purity  and  then 
examine  with  the  spectro- 
scope. Very  small  traces  of 
lithium,  for  instance,  may 
be  detected  as  follows  :  To 
about  a  liter  of  the  water 
sufficient  sodium  carbonate 
is  added  to  precipitate  all 
the  calcium  and  magne- 
sium, and  the  liquid  boiled 
down  to  about  one-tenth 

its  bulk ;  it  is  then  filtered,  the  filtrate  rendered  slightly 
acid  with  hydrochloric  acid  and  evaporated  to  dryness. 
The  residue  is  boiled  with  a  little  alcohol,  which  will  dis- 
solve out  the  lithium  chloride.  The  alcoholic  solution  is 
evaporated  to  dryness,  the  residue  taken  up  with  a  little 
water  and  tested  in  the  flame. 

In  order  to  identify  with  certainty  any  line  which  may 
be  obtained,  it  is  only  necessary  to  hold  in  the  flame  at 


68  ANALYTICAL  OPERATIONS. 

the  same  time  a  wire  which  has  been  dipped  in  a  solution 
of  the  substance  supposed  to  be  present,  and  to  note 
whether  the  lines  produced  by  it  and  the  material  under 
examination  are  identical. 

SPECIFIC  GRAVITY. 

In  the  great  majority  of  cases  the  determination  of 
specific  gravity  is  not  essential.  Ordinary  river,  spring  and 
well  waters  contain  such  small  proportions  of  solid  matter 
that  it  is  usually  the  practice  to  take  a  measured  volume 
and  to  assume  its  weight  to  be  that  of  an  equal  bulk  of 
pure  water.  If  the  proportion  of  solids  be  high,  a  deter- 
mination of  the  specific  gravity  may  be  desirable.  For 
this  purpose  the  specific  gravity  bottle  may  be  used.  This 
consists  merely  of  a  small  flask  provided  with  a  finely  per- 
forated glass  stopper.  The  bottle  is  weighed  first  alone, 
then  filled  with  distilled  water  at  60°  F.,  and  finally  with 
the  water  under  examination  at  the  same  temperature.  In 
filling  the  bottle,  the  liquid  is  first  brought  to  the  proper 
temperature,  the  bottle  completely  filled,  the  stopper  in- 
serted, and  the  excess  of  water,  forced  out  through  the 
perforation  and  around  the  sides  of  the  stopper,  carefully 
removed  by  bibulous  paper.  The  weight  of  the  water 
examined  divided  by  the  weight  of  the  equal  bulk  of  dis- 
tilled water  at  the  same  temperature  gives  the  specific 
gravity. 

Another  method,  and  one  which  gives  very  satisfactory 
results,  is  by  the  use  of  a  plummet.  This  may  convenient- 
ly consist  of  a  piece  of  thick  glass  rod  of  about  10  c.  c.  in 
bulk,  or  of  a  test-tube  weighted  with  mercury  and  the  open 
end  sealed  in  the  flame.  The  plummet  is  suspended  to  the 
hook  of  the  balance  by  means  of  a  fine  platinum  wire  and 


TECHNICAL    EXAMINATIONS.  69 

its  weight  ascertained.  It  is  then  immersed  in  distilled 
water  at  60°  F.  and  the  loss  in  weight  noted.  The  figure  so 
obtained  is  the  weight  of  a  bulk  of  water  equal  to  that  of 
the  plummet.  This  having  been  determined,  the  specific 
gravity  of  any  water  may  be  found  by  immersing  in  it  the 
plummet  and  noting  the  loss  in  weight.  This,  divided  by 
the  loss  suffered  in  pure  water,  gives  the  specific  gravity. 


INTERPRETATION  OF  RESULTS. 

STATEMENT  OF  ANALYSIS. 

The  composition  of  water  is  generally  expressed  in  terms 
of  a  unit  of  weight  in  a  definite  volume  of  liquid,  but  much 
difference  exists  as  to  the  standard  used.  The  decimal 
system  is  very  largely  employed,  the  proportions  being 
expressed  in  milligrams  per  liter,  nominally  parts  per  mil- 
lion ;  or  in  centigrams  per  liter,  nominally  parts  per  hund- 
red thousand.  Not  infrequently  the  figures  are  given  in 
grains  per  imperial  gallon  of  70,000  grains,  or  the  U.  S. 
gallon  of  58,328  grains.  Much  more  rarely  grains  per 
quart,  parts  per  thousand,  per  cent,  or  other  inconvenient 
ratios  are  employed.  In  this  work  the  composition  is 
always  expressed  in  parts  per  million.  This  ratio  is  practi- 
cally equivalent  to  milligrams  per  liter,  except  in  cases  of 
waters  very  rich  in  solids,  a  liter  of  which  weighs  notably 
more  than  one  million  milligrams.  Factors  for  converting 
the  different  ratios  are  given  at  the  end  of  the  book. 

From  the  analysis  of  a  water  it  is  rarely  possible  to  ascer- 
tain the  exact  arrangement  of  the  elements  determined,  but 
it  is  the  custom  to  assume  arrangements  based  upon  the 
rule  of  associating  in  combination  elements  having  the 
highest  affinities,  modifying  this  system  by  any  inferences 
derived  from  the  character  or  reactions  of  the  water  itself. 
It  has  been  demonstrated  that,  even  in  the  case  of  mixtures 
of  salts  producing  no  insoluble  substances,  partial  inter- 

70 


STATEMENT   OF    ANALYSIS.  71 

change  of  the  basylous  and  acidulous  radicles  takes  place. 
In  a  solution  of  sodium  chloride  and  potassium  sulphate, 
sodium  sulphate  and  potassium  chloride  will  be  found,  as 
well  as  the  original  salts.  When  the  conditions  are  ren- 
dered more  complex  by  the  addition  of  other  substances, 
it  is  obviously  impossible  to  determine  the  exact  arrange- 
ment. In  view  of  these  facts,  it  is  preferable  to  express 
the  composition  of  a  water  by  the  proportion  of  each  ele- 
ment or  radicle  present.  In  this  way  a  water  containing 
K2SO4,  will  be  expressed  in  terms  of  K  and  SO4,  respec- 
tively. In  the  case  of  bodies  like  CO2  and  SiO2,  which  may 
possibly  exist  free  in  the  water,  their  proportion  is  expressed 
as  such.  It  frequently  occurs  that  the  characteristics  of 
some  of  the  compounds  in  a  water  are  sufficiently  marked 
to  indicate  their  presence,  and  there  can  be  no  objection 
to  suggesting  in  connection  with  the  analytical  statement, 
the  inferences  which  may  thus  be  drawn. 

The  organic  matter,  or  its  derived  products,  are  best 
stated  in  terms  of  the  nitrogen  which  they  contain,  thus 
permitting  a  comparison  of  the  different  stages  of  decom- 
position. It  is  inadvisable  to  represent  the  amount  of 
unchanged  organic  matter  in  terms  of  oxalic  acid,  as  has 
been  suggested,  or  to  express  the  nitrogen  in  terms  of  albu- 
min, or  any  other  supposititious  compound. 

SANITARY  APPLICATIONS. 

Judgment  upon  the  analytical  results  from  a  given  sam- 
ple of  water  depends  upon  the  class  to  which  it  belongs, 
and  to  the  particular  influences  to  which  it  has  been  sub- 
jected. A  proportion  of  total  solids  which  would  be  sus- 
picious in  a  rain  or  river  water,  would  be  without  signifi- 
cance in  that  from  an  artesian  well.  On  the  other  hand,  a 


72  INTERPRETATION    OF    RESULTS. 

subsoil  water  of  unobjectionable  character  would  contain  a 
proportion  of  nitrates  which  would  be  inadmissible  in  the 
case  of  a  river  or  deep  water.  Location  has  also  much 
bearing  in  the  case;  subsoil  waters  near  the  sea  will  be 
found  to  contain,  without  invoking  suspicion,  proportions 
of  chlorine  which  would  be  ample  to  condemn  the  same 
sample  if  derived  from  a  point  far  inland.  Hence  the  im- 
portance of  recording  at  the  time  of  collection,  all  ascertain- 
able  information  as  to  the  surroundings  and  probable  source 
of  the  water. 

Color,  Odor  and  Taste. — Water  of  the  highest  purity 
will  be  clear,  colorless,  odorless,  and  nearly  tasteless. 
While  in  some  cases  a  decided  departure  from  this  standard 
may  give  rise  to  suspicion,  analytical  observations  are 
necessary  to  decide  the  point.  Water  highly  charged  with 
mineral  matters  will  possess  decided  taste,  vegetable  mat- 
ters may  communicate  distinct  color;  but,  on  the  other 
hand,  it  may  be  highly  contaminated  with  dangerous  sub- 
stances and  give  no  indications  to  the  senses.  Well-waters 
occasionally  become  offensive  in  odor,  from  penetration 
of  tree  roots.  The  odor  often  recalls  that  of  hydrogen 
sulphide.  Sulphides  are,  indeed,  often  formed  in  such 
cases  by  the  abstraction  of  oxygen  from  sulphates  under 
the  influence  of  microbes.  Such  waters  are  often  used 
without  apparent  injury,  but  it  is  probable  that  if  direct 
pollution  occurs,  the  danger  would  be  enhanced  by  the 
presence  of  the  vegetable  matter.  Miquel  has  described 
a  bacillus,  under  the  name  B.  sulphydrogenus,  which  pro- 
duces hydrogen  sulphide  readily.  Some  of  the  common 
putrefactive  bacilli  doubtless  have  this  power  also,  largely 
through  the  influence  of  the  hydrogen  liberated  by  them. 
In  waters  containing  hydrogen  sulphide,  species  of  beg- 


SANITARY   APPLICATIONS.  73 

giatoa,  especially  B.  alba,  thrive,  and  decomposing  the 
sulphide,  become  impregnated  with  sulphur.  Natural  sul- 
phur waters  frequently  contain  these  organisms,  as  do,  also, 
waste-waters  containing  sulphide. 

Total  Solids. — Excessive  proportions  of  mineral  solids, 
especially  of  marked  physiological  action,  are  known  to 
render  water  non-potable,  but  no  absolute  maximum  or 
minimum  can  be  assigned  as  the  limit  of  safety.  Distilled 
water  and  waters  very  highly  charged  with  mineral  matter 
have  been  used  for  long  periods  without  ill  effects.  The 
popular  notion  that  the  so-called  hard  waters  conduce  to 
the  formation  of  urinary  calculi  is  not  borne  out  by  surgical 
experience  nor  statistical  inquiry.  Many  urinary  calculi 
are  composed  of  uric  acid,  and  are  the  results  of  disorders 
of  the  general  nutritive  functions. 

Sanitary  authorities  have  fixed  an  arbitrary  limit  of  total 
solids  of  about  six  hundred  parts  per  million,  but  many 
artesian  waters  in  constant  use  exceed  this.  An  instance 
is  found  in  the  well  on  Black's  Island,  near  Philadelphia, 
given  in  the  table  of  analyses,  which  contains  nearly  twelve 
hundred  parts  per  million,  is  very  agreeable  in  taste,  and 
has  been  in  constant  use  for  some  years  by  a  number  of 
persons  without  injury.  The  assertion  that  water  to  be 
wholesome  must  contain  an  appreciable  proportion  of  total 
solids  is  also  not  demonstrated  by  clinical  experience.  A 
discussion  of  the  effects  of  special  mineral  ingredients,  e.  g., 
magnesium  sulphate,  ferrous  carbonate,  etc.,  belongs  to 
general  therapeutics. 

The  odor  produced  on  heating  the  water  residue  is  often 

of  much  use  in  detecting  contamination.     Odors  similar 

to  those  produced  by  heating  glue,  hair,  rancid  fats,  urine, 

or  other  animal  products,  will  give  rise  to  grave  suspicion. 

F 


74  INTERPRETATION    OF    RESULTS. 

On  the  other  hand,  a  more  favorable  judgment  may  be 
given  when  the  odor  recalls  those  given  off  in  the  heating 
of  non-nitrogenized  vegetable  materials,  such  as  wood- 
fibre. 

Poisonous  Metals. — The  proportion  of  iron  in  water 
constantly  used  for  drinking  purposes  should  not  much 
exceed  three  parts  per  million.  Lead,  copper,  arsenic 
and  zinc  must  be  considered  dangerous  in  any  amount, 
though  it  appears  that  zinc  and  copper,  being  least  cumu- 
lative, are  rather  less  objectionable  in  minute  amount  than 
the  others.  Concerning  the  limit  of  safety  with  mangan- 
ese and  chromium  very  little  is  known,  but  their  presence 
in  appreciable  quantity  must  be  looked  upon  with  sus- 
picion. 

Chlorides  and  Phosphates. — Chlorides — principally 
sodium  chloride — and  phosphates  are  abundantly  distrib- 
uted in  rocks  and  soils,  and  find  their  way  into  natural 
waters  ;  but  while  the  former  are  freely  soluble,  and  remain 
in  undiminished  amount  under  all  conditions  to  which  the 
water  is  subjected,  all  but  minute  amounts  of  the  latter  are 
either  precipitated  or  removed  by  the  action  of  living 
organisms.  Surface  and  subsoil  waters  ordinarily  contain 
but  a  few  parts  per  million.  Both  chlorides  and  phos- 
phates being  constant  and  characteristic  ingredients  of 
animal  excretions,  it  is  obvious  that  an  excess  of  them  in 
natural  waters,  unless  otherwise  accounted  for,  will  suggest 
direct  contamination.  Proximity  to  localities  in  which 
sodium  chloride  is  abundant,  such  as  the  sea  or  salt  de- 
posits, will  deprive  the  figure  for  the  chlorine  of  diagnostic 
value,  nor  can  any  indication  of  sewage  or  other  danger- 
ous pollution  be  inferred  from  high  proportion  of  chlorine 
in  deep  waters.  Further,  it  has  been  shown  that  the  pro- 


SANITARY   APPLICATIONS.  75 

portion  of  chlorine  in  uncontaminated  waters  is  tolerably 
constant,  while  in  water  subjected  to  the  infiltration  of 
sewage,  the  chlorine  undergoes  marked  variation  in  amount. 
In  most  cases,  therefore,  a  correct  judgment  can  only  be 
attained  by  comparison  with  the  average  character  of  the 
waters  of  the  same  type  in  the  district,  and  by  examination 
at  intervals  of  the  water  in  question. 

As  regards  phosphates,  Hehner,  who  has  published  a 
series  of  analyses,  states  that  the  presence  of  more  than  0.6 
parts  per  million — calculated  as  PO4 — should  be  regarded 
with  suspicion.  On  the  other  hand,  the  absence  of  phos- 
phates affords  no  positive  proof  of  the  freedom  from  pollu- 
tion. The  application  of  Heisch's  test  will  often  afford 
additional  information  on  this  point.  F.  E.  Lott,  who 
has  applied  this  test  in  the  examination  of  a  number  of 
waters,  fully  confirms  Dr.  Frankland's  statement  that  the 
development  is  due  to  phosphates,  and  draws  the  following 
conclusions:  — 

Any  water  which  undergoes  butyric  fermentation  when 
simply  treated  with  cane  sugar  and  kept  at  a  temperature  of 
80°  F.,  may  be  at  once  condemned  as  unfit  for  domestic  use. 

The  single  fact  of  a  water  not  undergoing  butyric  fer- 
mentation is  no  proof  of  its  purity. 

A  water  which  remains  clear  under  this  treatment  would 
certainly  be  less  likely  to  be  contaminated  by  sewage  than 
one  which  becomes  milky,  and  the  possibility  of  unoxid- 
ized  sewage  matter  being  in  a  water  which  remains  quite 
clear  is  very  doubtful. 

The  butyric  ferment  is  not  perceptibly  influenced  by  the 
presence  of  abnormal  amounts  of  chlorine,  ammonia,  nitro- 
genous matter,  sulphates  or  nitrates,  but  is  a  very  accurate 
indicator  of  the  presence  of  phosphates. 


76  INTERPRETATION    OF   RESULTS. 

Nitrogen  from  Ammonium  Compounds. — Ammo- 
nium compounds  are  usually  the  results  of  the  putrefactive 
fermentation  of  nitrogenous  organic  matter  ;  they  may  also 
be  the  product  of  the  reduction  of  nitrites  and  nitrates 
in  presence  of  excess  of  organic  matter.  In  either  case, 
therefore,  they  suggest  contamination.  Deep  waters  often 
contain  an  excess  of  ammonium  compounds,  derived,  in 
large  part,  from  the  reduction  of  nitrates.  Their  presence 
here  is  hardly  ground  for  adverse  judgment,  since  the 
water,  even  though  originally  contaminated,  has  undergone 
extensive  filtration  and  oxidation  and  its  organic  matter 
converted  into  bodies  presumably  harmless.  §uch  waters, 
indeed,  usually  show  only  traces  of  unchanged  organic 
matter. 

Rain  water  often  contains  large  proportions  of  ammo- 
nium compounds ;  but  here,  also,  the  fact  cannot  condemn 
the  water,  since  it  does  not  indicate  contamination  with 
dangerous  organic  matter. 

The  evolution  of  ammonia  in  the  distillation  of  rain  water 
often  continues  indefinitely,  the  larger  portion  passing  over 
in  the  first  distillates,  but  small  quantities  being  present 
even  after  the  distillation  has  been  much  prolonged.  The 
same  continuous  evolution  of  ammonia  is  noted  in  waters 
containing  urea,  but  in  this  case  a  larger  proportion  is 
collected  in  the  earlier  distillates,  nearly  all  coming  over 
before  one-half  the  water  has  been  distilled.  Fox  gives 
the  following  figures  as  ratios  obtained  in  the  analysis  of 
two  samples,  one  of  rain  water  collected  from  a  roof  and 
therefore  impure,  and  the  other  of  a  water  containing 
urine : — 


SANITARY   APPLICATIONS.  77 

RAIN  WATER.      URINE  WATER. 

1st  distillate, 35  .38  parts  per  million. 

2d  "  25  .14 

3d  "  12  .065  "  " 

4th  "  09  .035 

5th  "  09 

6th  "  04  .    .  " 

7th  "  03 

.97  .620 

Nitrogen  by  Alkaline  Permanganate  (Nitrogen  of 
"albuminoid  ammonia"). — A  large  yield  of  ammonia  by 
boiling  with  alkaline  potassium  permanganate  will,  of 
course,  point  to  an  excess  of  nitrogenous  organic  matter. 
The  inferences  to  be  drawn  depend  upon  the  origin  and 
condition  of  the  organic  material.  If  animal,  the  water 
may  at  once  be  condemned  as  unsafe.  Waters  containing 
excessive  amounts  even  of  vegetable  matter  are  not  free 
from  objection,  since  they  have  frequently  caused  persistent 
diarrhoea.  If  the  organic  matter,  whether  animal  or 
vegetable,  is  in  a  state  of  active  decomposition,  it  is  doubly 
objectionable.  Mallet  has  called  attention  to  the  fact  that 
such  waters,  as  a  rule,  yield  ammonia  rapidly,  whereas 
non-decomposing  material  yields  it  but  slowly,  and  he 
points  out  the  importance,  therefore,  of  noting  the  rate  at 
which  the  ammonia  collects  in  the  distillate. 

Dr.  Smart  has  observed  that  water  containing  fermenting 
vegetable  matter  is  colored  yellow  by  boiling  with  sodium 
carbonate,  and  that  when  Nessler's  reagent  is  added  to  the 
distillate,  a  greenish,  in  place  of  the  ordinary  yellowish- 
brown  color  is  produced.  He  applies  this  fact  in  con- 
junction with  the  determination  of  the  oxygen-consuming 


78  INTERPRETATION    OF    RESULTS. 

power  (Tidy's  process)  and  the  rate  of  evolution  of  the 
ammonia  by  alkaline  permanganate  as  follows  :  — 

A  water  yielding  ammonia  slowly  by  alkaline  perman- 
ganate, contains  recent  organic  matter;  of  animal 
derivation,  if  the  oxygen-consuming  power  is  low  \  of 
vegetable,  if  high. 

A  water  yielding  ammonia  more  rapidly  by  alkaline  per- 
manganate, shows  decomposing  organic  matter  ;  of  animal 
origin,  if  the  oxygen-consuming  power  be  low  and  there 
be  no  interference  with  the  Nessler  reaction  ;  of  vegetable 
origin,  if  the  oxygen  consumed  be  high,  and  if  a  yellow 
color  be  produced  in  the  water  by  sodium  carbonate,  and  a 
greenish  color  in  the  nesslerized  distillate. 

Inferences  as  to  the  source  of  the  organic  matter  can 
usually  be  drawn  from  the  amount  of  chlorine  and  nitrates 
present.  If  the  chlorine  be  high  /.  e.,  in  excess  of  the 
average  of  the  district,  it  may  be  inferred  that  the  material 
is,  in  great  part,  of  animal  origin.  In  this  case,  the  nitrates 
will  either  be  high  or  entirely  absent,  according  as  the 
contaminating  matter  has  passed  through  soil  or  enters  the 
water  directly. 

A  large  amount  of  vegetable  matter  will,  as  a  rule,  show 
itself  by  the  color  it  imparts  to  the  water. 

Wanklyn  gives  the  following  standards  :  — 

High  purity, oo    to  .041  per  million. 

Satisfactory  purity,      041  to  .082     "         " 

Impure, over    .082. 

In  the  absence  of  ammonium  compounds,  he  does  not 
condemn  a  water  unless  the  nitrogen  by  permanganate  ex- 
ceeds .081  per  million ;  but  a  water  yielding  0.123  parts 
per  million  of  nitrogen  by  permanganate  he  condemns 
under  all  circumstances. 


SANITARY   APPLICATIONS.  79 

Total  Nitrogen. — Drown  and  Martin's  results  with 
surface  waters  indicate  that  the  total  nitrogen  obtained  by 
their  process  is  about  twice  that  obtained  by  alkaline  per- 
manganate. Our  own  experiments  accord  with  this.  Further 
observation  on  different  waters  and  by  different  observers 
will  be  required  to  determine  the  value  to  be  assigned  to 
the  figures  obtained  by  this  method.  This  method  is 
especially  suitable  for  studying  the  effects  of  filtration, 
storage,  etc.,  on  the  nitrogenous  organic  matter  in  water. 

Nitrogen  as  Nitrites. — Nitrites  are  present  in  water 
as  the  result  either  of  incomplete  nitrification  of  ammonia, 
or  the  reduction  of  already  formed  nitrates,  under  the  in- 
fluence of  reducing  agents  or  microbes.  Since  they  are 
transition  products,  their  presence  in  water  is  usually  evi- 
dence of  existing  fermentative  changes,  and,  further,  may 
be  taken  as  indicating  that  the  water  is  unable  to  dispose 
of  the  organic  contamination.  When,  however,  the  con- 
ditions are  such  that  oxidation  cannot  take  place,  nitrites 
may  persist  for  a  long  time.  This  sometimes  occurs  in 
deep  waters  in  which  fermentative  changes  have  long  since 
ceased,  but  oxygen  is  not  available.  These  contain  not 
infrequently  small  amounts  of  nitrites,  to  which  the  same 
degree  of  suspicion  cannot  be  attached.  When  nitrites 
are  found  in  these  waters,  the  possibility  of  their  introduc- 
tion from  polluted  subsoil  water,  through  defective  tubing, 
must  not  be  overlooked.  Rain  water,  also,  sometimes 
contains  nitrites  derived  from  the  air,  and  therefore  not 
indicative  of  any  putrefactive  change.  The  presence  of 
measurable  quantities  of  nitrites  in  river  or  subsoil  water 
is  sufficient  ground  for  condemnation. 

Nitrogen  as  Nitrates. — Nitrates  are  the  final  point  in 
the  oxidation  of  nitrogenous  organic  matter,  especially 


80  INTERPRETATION    OF    RESULTS. 

animal  matters.  Rain  water  and  that  from  mountain 
streams  and  deep  wells,  except  from  cretaceous  strata, 
generally  contain  only  traces,  but  river  and  subsoil  waters 
will  always  contain  appreciable  amounts,  unless  some  re- 
ducing action,  such  as  recent  sewage  pollution,  is  at  work. 
When,  therefore,  a  water  contains  enough  mineral  matter 
to  demonstrate  its  percolation  through  soil,  and  at  the  same 
time  is  free  from  nitrates  or  contains  only  traces,  the  oc- 
currence of  a  destructive  fermentation  may  be  inferred. 
These  cases  are  not  uncommon  among  well  waters,  and  the 
'samples  are  generally  turbid  from  suspended  organic  matter. 
Decided  departure,  either  by  increase  or  decrease,  from 
the  proportion  of  nitrates  usual  in  the  same  class  of  water 
in  any  district  may  be  taken  as  evidence  of  contamination. 

Oxygen-consuming  Power. — Sanitary  authorities 
differ  very  much  as  to  the  significance  of  this  datum.  At- 
tempts have  been  made  to  fix  maximum  limits  for  the 
various  types  of  water,  and  also  to  gauge  the  character  and 
condition  of  the  organic  matter  by  observing  the  rate  at 
which  the  oxidation  takes  place,  but  no  positive  conclu- 
sions can  be  given.  In  general,  it  may  be  said  that  a 
sample  which  has  high  oxygen.-consuming  power  will  be 
more  likely  to  be  unwholesome  than  one  which  is  low  in 
this  respect ;  but  the  interferences  are  so  numerous,  and  the 
susceptibility  to  oxidation  of  different  organic  matters  of 
even  the  same  type,  is  so  different,  that  the  method  is  at 
best  only  of  accessory  value.  It  is  especially  suitable  for 
consecutive  determinations  on  the  same  supply. 

The  following  proportions  are  given  by  Frankland  and 
Tidy  as  the  basis  of  interpreting  the  results  of  this 
method : — 


"* 


STATEMENT   OF    ANALYSIS.  8 1 

OXYGEN  ABSORBED    IN  THREE  HOURS. 

High  organic  purity, 05         parts  per  million. 

Medium  purity, 0.5  to  1.5      "     "         " 

Doubtful, 1.5  to  2.1      "     "         " 

Impure, over  2.1  "     "         " 

For  the  method  with  acidified  permanganate  at  the  boil- 
ing heat,  the  German  chemists,  who  employ  it  largely,  re- 
gard an  absorption  of  2.5  parts  of  oxygen  per  million  as 
suspicious,  and  some  sanitary  authorities  have  fixed  3.8  parts 
of  oxygen  per  million  as  the  highest  permissible  limit. 

Dissolved  Oxygen. — Full  aeration  of  water  is  favor- 
able to  the  destruction  of  organic  matter ;  a  decided  dimi- 
nution in  the  quantity  of  dissolved  oxygen  may  show  excess 
of  such  matter  and  of  microbic  life.  Gerardin  has  pointed 
out  that  this  diminution  is  associated  with  the  development 
of  low  forms  of  vegetable  life,  and  Leeds  has  recorded 
similar  facts.  These  changes  are  more  likely  to  take  place 
in  still  waters,  and  are  frequently  accompanied  by  disagree- 
able odor  and  taste.  In  cases  in  which  stored  waters  be- 
come unpalatable,  these  facts  should  be  borne  in  mind. 

Dupre  has  given  the  following  as  the  basis  for  interpret- 
ing the  results  of  his  adaptation  of  the  determination  of 
dissolved  oxygen  : — 

"  A  water  which  does  not  diminish  in  its  degree  of  aera- 
tion during  a  given  period,  may  or  may  not  contain  organic 
matter,  but  presumably  does  not  contain  growing  organ- 
isms. Such  organic  matter  as  it  may  be  found  to  contain 
by  chemical  analysis  need  not  be  considered  as  dangerous 
impurity." 

"  A  water  which  by  itself,  or  after  the  addition  of 
gelatin  or  other  appropriate  cultivating  matter,  consumes 
oxygen  from  the  dissolved  air,  at  lower  temperatures,  but 


82 


INTERPRETATION    OF    RESULTS. 


does  not  consume  any  after  heating  for,  say,  three  hours  at 
140°  F. ,  may  be  regarded  as  having  contained  living 
organisms,  but  none  of  a  kind  able  to  survive  exposure  to 
that  temperature." 

"  A  water  which  by  itself,  or  after  addition  of  gelatin  or 
the  like,  continues  to  absorb  oxygen  from  the  contained 
air  after  heating  to  140°  F.,  maybe  taken  as  containing 
spores  or  germs  able  to  survive  that  temperature." 

Hardness. — The  degree  of  hardness  has  but  little  bear- 
ing on  the  sanitary  value  of  water,  but  is  important  in 
reference  to  its  use  for  general  household  purposes,  in  view 
of  the  soap-destroying  power  which  hard  waters  possess. 


USUAL  ANALYTICAL   RESULTS    FROM 
UNCONTAMINATED   WATERS. 

Parts  per  million. 


Rain.' 

Surface. 

Subsoil. 

Deep. 

Total  solids,  

5  to  20 

15  upward 

30  upward 

45  upward 

Chlorine,     

Traces  to  i 

i  to  10 

2  tO  f2 

Traces  to  large 

Nitrogen  by  permanganate, 
as  NH4,   .... 

.08  to  .20 
.20  to  .50 

.05  to  .15 
.00  to  .03 

.05  to  .10 
.00  to  .03 

.03  to  .10 

Generally  high 

"         "  nitrites,    .    .    . 

None  or 
traces 

None 

None 

None  or  traces 

"          "  nitrates,  .    .    . 

Traces. 

.75  to  1.25 

i-5  to  5 

.00  to  3 

ACTION    OF   WATER   ON    LEAD.  83 

ACTION  OF  WATER  ON  LEAD. 

The  almost  universal  use  of  lead  pipes  for  conveying 
water,  and  the  facility  with  which  some  waters  corrode 
and  dissolve  the  metal,  make  it  a  question  of  moment  to 
determine  the  cause  of  this  action  and  to  devise  means  for 
its  prevention.  The  subject  has  received  considerable 
attention  within  the  last  few  years,  and  the  conditions  which 
determine  corrosion  are  now  fairly  understood.  As  a  rule, 
it  is  found  that  waters  free  from  mineral  matter  dissolve 
lead  with  facility,  especially  in  the  presence  of  oxygen. 
Some  very  soft  waters  are  entirely  without  action,  and 
this  was  unexplained  until  a  few  years  ago,  when  Messrs. 
Crookes,  Odling  and  Tidy  found  that  the  action  was  con- 
trolled by  the  amount  of  silica  contained  in  the  water. 
They  found  that  those  soft  waters  which,  when  taken  from 
the  service  pipes,  contained  a  notable  quantity  of  lead, 
gave,  on  the  average,  three  parts  of  silica  per  million ;  in 
those  in  which  there  was  no  lead,  the  silica  present 
amounted  to  7.5  per  million  and  in  those  in  which  the 
action  was  intermediate,  5.5  parts  per  million.  That  it 
was  really  the  silica  that  conditioned  the  corrosion,  was 
confirmed  by  laboratory  experiments.  They  also  found 
that  the  most  effective  way  of  silicating  a  water  is  by  passing 
it  over  a  mixture  of  flint  and  limestone.  The  reason  for 
this  was  pointed  out  later  by  Messrs.  Carnelly  and  Frew, 
who  showed  that  while  calcium  carbonate  and  silica  both 
exert  a  protective  influence,  calcium  silicate  is  more 
effective  than  either,  and  further,  that  in  almost  all  cases 
in  which  corrosion  took  place  it  was  greater  in  the  presence 
of  oxygen.  This  is  particularly  the  case  with  potassium 
and  ammonium  nitrates  and  with  calcium  hydroxide.  The 


84  INTERPRETATION    OF    RESULTS. 

reverse  is  true  of  calcium  sulphate,  which  is  more  corrosive 
when  air  is  excluded.  Their  experiments  also  show  that  the 
presence  of  calcium  carbonate  or  calcium  silicate,  altogether 
prevents  corrosion  by  potassium  and  ammonium  nitrates. 

As  the  result  of  an  elaborate  series  of  experiments,  Miil- 
ler  concludes,  that  while  chlorides,  nitrates  and  sulphates 
all  act  upon  lead  pipes,  no  corrosion  takes  place  in  the 
presence  of  sodium  acid  carbonate,  and  that  calcium  car- 
bonate, by  taking  up  carbonic  acid,  acts  in  the  same  way. 
This  latter  conclusion  is  at  variance  with  the  observations 
of  Carnelly  and  Frew,  who  found  that  calcium  carbonate 
is  equally  effective  when  carbonic  acid  is  excluded.  Miil- 
ler  also  states  that  surface  waters,  contaminated  by  sewage 
and  containing  large  amounts  of  ammoniacal  compounds, 
will  dissolve  lead  under  all  circumstances. 

Allen  has  shown  that  water  containing  free  acid,  in- 
cluding sulphuric  acid,  acts  energetically  upon  lead.  This 
is  not  surprising  in  view  of  the  later  experiments,  which 
prove  that  even  calcium  sulphate  is  corrosive.  Later,  W. 
Carleton-Williams  found  that  even  in  the  presence  of  free 
acid,  corrosion  may  be  prevented  by  the  addition  of  suffi- 
cient silica.  His  experiments  also  confirm  the  view  gener- 
ally held,  that  soluble  phosphates  protect  lead  to  a  marked 
degree. 

The  following  is  a  summary  of  the  more  important  ob- 
servations on  this  subject : — 

Corrosive :  Free  acid  or  alkalies,  oxygen,  nitrates,  par- 
ticularly potassium  and  ammonium  nitrates,  chlorides  and 
sulphates. 

Non-corrosive  and  preventing  corrosion  by  the  above : 
Calcium  carbonate,  sodium  acid  carbonate,  ammonium 
carbonate,  calcium  silicate,  silica  and  soluble  phosphates. 


SANITARY   APPLICATIONS.  85 

BIOLOGICAL  EXAMINATIONS. 

In  a  comprehensive  sense  the  living  organisms  of  water 
include  representatives  of  all  the  great  groups  of  animals 
and  plants.  The  presence  of  any  of  the  higher  orders  of 
organic  forms  may  be  taken  as  an  indication  of  moderate 
purity,  as  these  are  absent  from  very  foul  water.  From  an 
analytical  point  of  view,  observation  is  limited  to  the  deter- 
minations of  those  forms  which  are  inappreciable  to  the 
unassisted  eye.  As  far  as  regards  some  of  the  moderately 
complex  organisms,  such  as  the  minute  crustaceans,  algae, 
desmids,  and  even  the  amoebae,  it  may  be  said  that  while 
some  general  inferences  as  to  the  character  and  history  of 
the  water  may  be  deduced  from  an  identification  of  the 
specific  forms,  no  definite  sanitary  signification  can  be 
attached  to  them.  The  ova  of  the  entozoa  might  in  some 
cases  be  detected  by  careful  search,  and  would  indicate 
recent  pollution  of  a  highly  dangerous  character. 

Cohn  (Beitr.  z.  Biol.  d.  Pflanz.}  regards  chlorophyll- 
producing  plants  (diatoms  and  green  algae),  together  with 
the  infusoria  that  feed  upon  them,  and  species  of  entomos- 
traca  (Daphnia  and  Cyclops},  when  present  in  only  moderate 
amounts,  as  indicating  water  not  very  rich  in  dissolved 
organic  matter.  Species  of  Cladotkrix,  Crenothrix  and 
Beggiatoa,  which  are  among  the  larger  bacteria,  and  fre- 
quently appear  as  branching  forms,  indicate  suspended 
organic  matter;  while  dissolved  organic  matter  in  a  state 
of  active  decomposition  is  indicated  by  the  presence  of 
ordinary  bacteria  (Bacilli,  Spirt  llfy,  etc. 

Cladothrix  dichotoma  withdraws  iron  from  water,  and 
fixes  it,  causing  obstructions  in  iron  water  pipes.  Creno- 
thrix Kuhniana,  Rabenhorst,  is  seen  in  water  containing 
iron  and  sometimes  causes  a  disagreeal 


86 


BIOLOGICAL    EXAMINATIONS. 


FIG.  10. 


The  number  of  the  higher  forms  present  in  any  sample 
will  depend  very  much  upon  the  point  at  which  it  is  col- 
lected, they  being  more  numerous  in  the  neighborhood  of 
large  plants  and  at  the  bottom  and  sides  of  streams. 
Under  our  present  knowledge,  no  pathogenic  power  can 
be  assigned  to  the  higher  forms  of  organic  life,  except 
entozoa,  but  their  bodies  after  death  may  indirectly  con- 
tribute to  the  rapid  increase  of  the  bacilli  proper,  by  serving 
as  food. 

Instances  of  the  introduction  of  the  ova  of  entozoa 
into  the  human  system  by  means  of  water  are  doubtless 
very  common,  and  cases  have  been  reported.  One  of  the 
most  striking  of  these  was  the  anaemia  occurring  among 
the  workmen  in  the  St.  Gothard  tunnel,  which  was  found  to 
be  due  to  the  ingestion  of  the  ova  of  a  parasitic  animal,  An- 

chylostomum  duodenale. 
Culture  Media. — 
For  bacteriological  ex- 
aminations, culture 
media  prepared  with 
gelatine  or  agar-agar, 
are  generally  used.  In 
special  cases  potatoes 
and  blood  -  serum  are 
employed.  In  all  cases 
solutions  and  vessels 
must  be  thoroughly 
sterilized.  This  is  most 
easily  accomplished  in 
the  Arnold  steam  steril- 
izer, shown  in  Fig.  TO. 
It  consists  of  a  copper 
boiler,  A,  in  the  form  of  an  inverted  funnel,  which  com- 


SANITARY    APPLICATIONS.  87 

municates  with  the  sterilizing  chamber.  A  double  casing 
is  so  arranged  that  the  condensed  steam  falls  into  the  pan 
B  and  returns  to  the  boiler.  This  pan  should  be  about 
half-filled  with  water  before  starting.  We  have  found  this 
apparatus  suitable  not  only  for  all  sterilizations,  but  also 
for  preparing  solutions  and  for  hot  filtrations. 

Meat-extract-peptone-gelatin : — 

Water, looo  c.c. 

Meat  extract  (Armour's), 5  grams 

Gelatin  (best  French), 150     " 

Peptone  (Merck's,  dry), 10     " 

Glucose  (best), 2     " 

The  materials  are  dissolved  by  heat  and  the  solution 
rendered  slightly  alkaline  by  the  addition  of  sodium  car- 
bonate or  trisodium  phosphate,  added  by  small  portions, 
stirring  between  each  addition,  and  testing  the  liquid  by 
placing  a  drop  of  it  on  red  litmus  paper.  When  the  alka- 
line reaction  appears,  the  liquid  is  filtered  through  good 
filter  paper,  the  funnel  and  beaker  being  placed  in  the 
sterilizer,  and  a  gentle  steaming  maintained  in  order  to 
keep  the  gelatin  liquid. 

In  place  of  meat  extract,  a  solution  may  be  made  as  fol- 
lows:  macerate  500  grams  of  finely  minced  lean  meat  in 
i ooo  c.c.  of  water,  for  twenty-four  hours,  at  a  temperature 
not  over  45°  F.  Strain  the  liquid,  add  five  grams  of 
common  salt  and  the  peptone,  gelatin  and  glucose,  and 
render  feebly  alkaline,  as  before. 

Agar-agar  Mixture. — When  cultures  are  to  be  conducted 
at  a  temperature  above  68°  F.,  agar-agar  must  be  used  as 
gelatinizing  ingredient.  The  solution  is  prepared  as  given 
above,  except  that  only  15  grams  of  agar-agar  must  be 


88  BIOLOGICAL    EXAMINATIONS. 

used  and  a  much  longer  time  will  be  required  for  its  solu- 
tion. The  operation  can  be  facilitated  by  soaking  the 
agar-agar  for  twelve  hours  in  a  strong  solution  of  common 
salt,  or  by  the  following  treatment,  which  was  first  described 

20  grams  of  agar-agar,  cut  fine,  are  steepecLin  500  c.c.  of 
water,  containing  six  per  cent,  of  hydrochloric  acid,  with 
occasional  stirring.  It  is  then  well  washed,  and  placed  for 
a  similar  period  in  the  same  amount  of  water,  to  which  six 
per  cent,  of  ammonium  hydroxide  has  been  added.  It  is 
again  washed  thoroughly  and  added  to  1000  c.c.  of  boiling 
water.  It  dissolves  at  once.  The  peptone,  gelatin  and 
salt  can  then  be  added,  the  mixture  rendered  feebly  alka- 
line and  filtered  in  the  sterilizer. 

Agar-agar  Gelatin. — To  secure  the  advantages  of  both 
agar-agar  and  gelatin,  a  solution  may  be  made  by  dissolv- 
ing 50  grams  of  gelatin  and  7.5  grams  of  agar-agar  in  a 
liter  of  water,  adding  the  peptone,  etc.  in  the  usual  pro- 
portions, rendering  alkaline,  filtering  and  sterilizing.  The 
proportions  of  agar-agar  and  gelatin  must  be  adhered  to 
closely  or  the  gelatinization  may  be  lumpy  and  incomplete. 

Potato  Culture. — Cultivation  on  potatoes  is  an  important 
method  of  distinguishing  the  Bacillus  typhosus.  Large, 
sound  potatoes  should  be  selected,  thoroughly  washed, 
and  cut  into  disks  about  5  cm.  in  diameter  and  i  cm. 
thick.  These  are  placed  in  glass  boxes  (pomade  boxes) 
which  have  lids  with  ground  joint,  and  heated  for  about 
one-half  hour  in  the  sterilizer.  Another  method  is  to  cut 
out  cylinders  with  the  aid  of  an  apple-corer,  or  largest 
size  cork-borer,  slice  these  obliquely,  and  place  them  in 
test-tubes,  which  are  then  closed  with  cotton  plugs,  and 
sterilized.  The  latter  method  does  not  give  a  large  sur- 


SANITARY   APPLICATIONS.  89 

face,  but  the  growth  of  any  inoculation  may  be  easily 
watched. 

Collection  of  Samples. — Bacteriological  examinations 
are  of  little  value  unless  promptly  made  on  samples  that 
have  been  collected  with  precautions  against  contamina- 
tion. The  inoculation  of  the  culture  medium  is  best  done  at 
the  source.  If  this  is  not  possible,  glass  stoppered  bottles 
holding  about  200  c.c.,  which  have  been  thoroughly  steril- 
ized, with  stoppers  in  place,  in  a  hot  air  oven  at  300°  F., 
must  be  used  for  collection.  They  should  be  rinsed  on 
the  outside  with  water,  dipped  below  the  surface,  the 
stopper  withdrawn,  and  again  inserted  when  the  bottle  is 
full.  If  these  are  to  be  transported  any  distance  they 
should  be  packed  in  ice.  For  delivering  the  measured 
volume  of  water,  a  pipette  sterilized  in  the  hot-air  oven 
should  be  used. 

Culture  Manipulations. — For  the  estimation  and 
isolation  of  microbes  in  water,  we  may  employ  either  the 
original  plate  culture  of  Koch,  Esmarch's  "roll  culture," 
or  a  modification  that  we  have  used  in  our  own  work,  which 
may  be  designated  "  bottle  culture." 

Plate  Culture. — Test-tubes  containing  about  ten  c.c.  of 
nutrient  jelly  are  plugged  with  cotton  and  steamed  for 
fifteen  minutes  in  the  sterilizer  on  two  successive  days.  In 
filling  the  tubes,  care  must  be  taken  that  none  of  the  jelly 
touches  the  upper  part,  where  it  can  come  in  contact  with 
the  cotton  plug.  After  sterilization,  the  tubes  should  be 
put  aside  for  a  few  days,  to  determine  if  all  spores  are 
destroyed.  If  no  development  of  microbes  takes  place 
in  this  time,  the  jelly  is  ready  for  use.  It  should  be  melted 
at  a  low  temperature  in  a  water-bath,  the  cotton  plug  re- 
moved with  a  twisting  motion  and  a  measured  volume  of 
G 


90  BIOLOGICAL    EXAMINATIONS. 

water  introduced  by  means  of  a  sterilized  pipette.  The 
plug  is  immediately  replaced  and  the  liquids  mixed  by 
shaking,  taking  care  not  to  soil  the  cotton.  The  quantity 
of  water  to  be  added  will  depend  on  the  number  of 
microbes  supposed  to  be  present.  If  the  amount  is  pro- 
bably quite  small,  i  c.  c.  should  be  taken  ;  if  it  is  probable 
that  a  large  number  is  present,  i  c.  c.  of  the  sample 
should  be  diluted  to  10  c.c.  with  sterilized  water,  and  i  c.c. 
of  this  mixture  used.  In  most  cases  it  will  be  well  to  make 
several  cultures,  using  different  proportions  of  water.  After 
the  jelly  and  water  have  been  mixed  the  liquid  is  poured 
out  on  a  glass  plate  and  allowed  to  set.  The  principal 
difficulty  in  the  method  arises  from  the  liability  to  con- 
tamination from  the  air  during  this  part  of  the  process. 
The  glass  plates  should,  of  course,  be  thoroughly  sterilized. 
FIG  ti  They  are  usually  set  upon  glass 

benches,  and  placed  in  a  so-called 
moist  chamber,  which  consists  of 
two  cylindrical  glass  dishes,  one 
fitting  within  the  other  (Fig.  u). 
The  benches  and  plates  are  placed 
in  the  inner  dish.  To  hasten  the  setting  of  the  jelly,  it  is 
necessary  that  the  plates  should  be  cold,  and  it  will  be  best 
to  have  them  resting  in  a  level  position  on  a  flat  tin  bottle 
filled  with  ice  water,  or,  if  ice  is  not  at  hand,  a  recently 
prepared  mixture  of  one  part  of  ammonium  nitrate  with 
two  parts  of  water.  The  coated  plates  must  be  protected 
from  dust  while  being  cooled,  and  as  soon  as  possible 
must  be  transferred  to  the  moist  chamber,  which,  as  well 
as  the  benches,  should  have  been  previously  thoroughly 
washed  with  recently  boiled  water.  The  bottom  should 
be  covered  with  a  sheet  of  moist  filter  paper.  The  plates 


SANITARY   APPLICATIONS.  9! 

are  kept  in  the  chamber  for  several  days.  Each  living 
microbe  that  is  capable  of  growing  in  the  jelly  will 
become  the  centre  of  a  colony  of  its  own  kind,  which  will 
soon  become  visible  to  the  naked  eye.  The  number  of 
colonies  may  be  counted  as  soon  as  they  are  distinct. 
When  the  number  is  very  large,  an  approximate  counting 
may  be  made  by  means  of  a  glass  plate  with  lines  ruled  so 
as  to  divide  it  into  a  considerable  number  of  equal  squares. 
This  is  placed  over  the  culture,  and  the  number  of  colonies 
in  several  of  the  squares  counted,  the  result  averaged  and 
multiplied  by  the  number  of  squares  that  the  entire  culture 
covers. 

Roll  Culture. — Instead  of  pouring  the  jelly  on  a  plate, 
it  may  be  spread  in  a  uniform  layer  on  the  inner  wall  of  the 
test-tube,  taking  care  not  to  allow  it  to  touch  the  cotton. 
The  jelly  may  be  rapidly  hardened  by  rolling  the  tube  in 
contact  with  ice.  The  method  avoids  all  danger  of  contam- 
ination with  dust  and  is  very  simple  in  manipulation, 
but  is  open  to  the  objection  that  when  bacilli  are  present 
which  liquefy  the  gelatine,  as  will  generally  be  the  case,  the 
fluid  will  run  down  and  inoculate  other  portions  of  the  layer. 

Bottle  Culture. — To  avoid  the  disadvantage  of  the 
above  methods,  it  will  be  found  convenient  to  employ  flat 
rectangular  bottles  of  the  form  known  technically  as  the 
"Blake"  Bottle.  Those  of  8  or  10  ounce  capacity  are 
the  best,  and  it  is  well  to  select  such  as  have  as  uniform  a 
thickness  of  glass  as  possible.  They  should  be  thoroughly 
cleaned  and  sufficient  of  the  jelly  put  in  to  form  a  thin  layer 
on  one  of  the  broader  sides  when  the  bottle  is  placed 
horizontally.  The  mouth  is  then  closed  by  a  cotton-plug 
and  the  bottle  sterilized  as  described  in  connection  with 
plate  culture.  To  make  a  culture,  the  jelly  is  melted  at  a 


92  BIOLOGICAL    EXAMINATIONS. 

low  temperature,  the  measured  volume  of  water  added, 
the  cotton  plug  replaced,  and  after  mixing,  the  bottle  is 
placed  in  a  horizontal  position  for  the  usual  time. 

General  Character  of  the  Microbes  in  Natural 
Waters. — The  microorganisms  of  natural  waters  are  prin- 
cipally included  in  the  genera  bacillus  and  spirillum, 
especially  the  former!  Micrococci  and  moulds  are  rare, 
and  when  they  appear  on  the  culture  plate,  are  generally 
due  to  contamination  by  dust. 

Microbes  are  distinguished  according  to  the  conditions 
favorable  to  their  growth,  as  follows  : — 

Saprophytic.     Growing  on  dead  matter.     • 

Parasitic.     Growing  only  on  living  matter. 

Aerobic.     Requiring  free  oxygen. 

Anaerobic.     Not  requiring  free  oxygen. 

When  the  organism  possesses  the  power  of  adapting  itself 
to  different  conditions,  the  term  facultative  is  applied ; 
when  it  can  grow  only  under  special  conditions,  the  term 
obligatory  is  applied. 

Thus,  the  Bacillus  butyricus  is  unable  to  develop  in 
contact  with  free  oxygen ;  it  is  an  obligatory  anaerobe. 
The  B.  typhosus  can  grow  either  on  dead  or  living  matter, 
and  though  growing  best  in  presence  of  free  oxygen,  can 
also  grow  in  the  absence  of  it.  It  is,  therefore,  a  faculta- 
tive saprophyte,  and  a  facultative  anaerobe. 

Microbes  are  also  differentiated  by  the  effect  which  they 
produce  upon  the  culture  medium.  Some  species  rapidly 
or  slowly  liquefy  the  jelly  with  evolution  of  foul  smelling 
gases;  others — chromogenic  microbes — produce  character- 
istic colors.  Many  do  not  produce  any  positive  modifica- 
tion, and  for  purposes  of  distinction  it  is  usual  to  transfer 
portions  of  the  colonies  to  other  culture  media.  Thus  the 


SANITARY   APPLICATIONS.  93 

B.  typhosus  causes  neither  liquefaction  nor  coloration,  but 
gives  a  distinct  growth  on  potato.  Such  special  cultures 
are  obtained  by  taking  up  a  portion  of  the  colony  on  the 
end  of  a  wire  which  has  been  just  sterilized  by  heating  to 
redness,  and  inoculating  the  prepared  medium. 

Cultivation  in  Absence  of  Oxygen. — Several  of  the  most 
frequently  occurring  microbes  are  obligatory  anaerobes, 
and  will  grow,  therefore,  only  in  an  atmosphere  deprived 
of  free  oxygen.  Carbon  dioxide  has  been  found  to  act 
unfavorably  upon  their  development.  The  most  suitable 
atmosphere  is  one  of  pure  hydrogen.  Cultivation  in 
such  an  atmosphere  may  be  secured  by  constructing  the 
moist  chamber  so  as  to  permit  its  being  filled  with 
hydrogen  and  sealed,  or  by  the  use  of  Liborius'  tube, 
Fig.  12. 

The  tube  is  charged  with  nutrient  jelly,        FIG.  12. 
plugged  with   cotton,   sterilized,  inoculated    I      I 
with  the  material  to  be  tested,  the  jelly  main-    \  / 
tained  in  a  liquid  condition  by  a  very  gentle    /  \ 
heat  and   a  current  of  pure  hydrogen  passed 
through   the   side   tube   until   all  air  is  ex- 
pelled.    The  test-tube  and  side  tube  are  then 
sealed    quickly   at    the    narrow   portions,  in 
the  blow-pipe  flame,  and    the  jelly  allowed 
to  solidify. 

Staining. — The  differentiation  of  the  various  species  of 
microbes  may  also  be  accomplished  by  staining  with  vari- 
ous aniline  colors.  These  methods  are,  however,  more 
generally  applicable  to  pathological  work,  that  is,  to  the 
staining  of  microbes  in  tissues;  but  one  of  the  methods  is 
here  described,  as  it  is  frequently  referred  to  in  bacterio- 
logical literature. 


94  BIOLOGICAL   EXAMINATIONS. 

Gram's  Method  of  Staining  (as  given  by  Crookshank). — 
Place  a  few  drops  of  pure  aniline  in  a  test-tube  three-fourths 
full  of  water,  and  shake  thoroughly.  Filter  the  emulsion 
twice,  collect  some  of  the  perfectly  clear  filtrate  in  a  watch- 
glass  and  add,  drop  by  drop,  a  concentrated  alcoholic  solu- 
tion of  gentian  violet,  until  precipitation  appears.  Stain 
sections  in  this  for  about  twenty  minutes,  then  place  them 
in  a  solution  prepared  as  follows  :  — 

Iodine, o.i  gram 

Potassium  iodide, 0.2     " 

Water, 30.0  grams. 

Allow  them  to  remain  until  dark  brown.  Decolorize  by 
placing  in  alcohol.  This  process  gives  blue  or  bluish-black 
microbes  in  a  background  tinged  faintly  yellow. 

Indol  Reaction. — Indol,  C8H7N,  more  properly  indine,  is 
a  weak  base,  which  is  a  product  of  the  growth  of  many 
species  of  microbes,  and  the  detection  of  it  may,  therefore, 
be  utilized  as  a  differentiation  test.  S.  Kitasato  (Zeit.  /. 
Hyg.  vn,  518)  gives  the  following  method  for  performing 
the  test : — 

Ten  c.  c.  of  an  alkaline-peptone-meat  infusion  (without 
gelatin),  which  has  been  previously  inoculated  with  the  mi- 
crobes to  be  tested,  and  kept  for  twenty-four  hours  at  blood 
heat,  are  treated  with  i  c.  c.  of  solution  of  pure  potassium 
nitrate  (0.02  grm.  in  100  c.  c.)  and  then  with  a  few  drops 
of  concentrated  sulphuric  acid.  In  the  presence  of  indol 
a  rose  or  deep-red  color  is  developed.  Spirillum  cholera 
gives  the  reaction  strongly ;  S.  Finkleri  feebly ;  Bacillus 
typhosus  does  not  give  it. 

Inferences  from  Culture. — Several  difficulties  inter- 
fere with  the  interpretation  of  bacteriological  cultures. 


SANITARY    APPLICATIONS.  95 

All  natural  waters  contain  microbes,  the  proportion  being 
subject  to  great  variation,  without  corresponding  variation 
in  sanitary  quality.  Many  of  the  forms  are  harmless  in 
any  proportion.  Their  number  is  subject  to  rapid  in- 
crease for  a  brief  period  after  collection  of  the  sample,  and 
may  be  greatly  modified  by  incidental  conditions  during 
storage  or  transportation,  so  that  little  value  can  be  attached 
to  quantitative  determinations,  except  when  made  without 
appreciable  delay.  The  culture  fluids  used,  and  the  condi- 
tions under  which  the  cultivation  takes  place,  do  not  suffice 
for  the  development  of  all  the  forms  present.  The  culti- 
vation ought  to  be  extended  over  many  days  and  different 
samples  of  the  same  water  tried  with  various  nutritive  media 
and  at  various  temperatures,  to  secure  a  full  knowledge  of 
the  microbes  present. 

As  an  indication  of  the  insufficiency  of  these  methods,  it 
may  be  mentioned  that  Miller  has  described  six  species 
of  microbes  occurring  in  the  human  mouth,  not  one  of 
which  will  grow  in  any  form  of  culture  medium  at  present 
known. 

While,  then,  these  examinations  are  as  yet  of  uncertain 
value  in  the  determination  of  the  potability  of  water,  they 
have  been  of  much  value  in  determining  the  effects  and 
usefulness  of  certain  conditions  to  which  water  is  subjected. 
In  these  studies  the  method  is  sufficiently  free  from  fallacy 
to  make  the  results  trustworthy.  By  it,  it  has  been  shown 
that  filtration  at  first  greatly  diminishes  the  number  of 
microorganisms,  but  subsequently,  owing  to  the  fouling  of 
the  filter,  and  partly  to  the  penetration  of  successive 
colonies  of  microbes  through  the  pores  of  the  filter,  the 
filtrate  becomes  richer  in  microbes  than  the  unfiltered 
water.  When  suspended  mineral  matters  are  caused  to 


g6  BIOLOGICAL    EXAMINATIONS. 

settle,  a  large  proportion  of  the  microbes  is  carried  down ; 
but  if  the  water  thus  purified  is  not  soon  removed,  the 
microbic  life  again  develops,  it  may  be  even  in  greater 
amount  than  was  originally  present.  The  storage  of  water 
at  first  increases  and  then  diminishes  the  number  present. 
The  presence  of  free  acid,  even  of  carbonic  acid,  is 
decidedly  inhibitory  to  their  development.  When  mi- 
crobes essentially  foreign  to  the  water  are  introduced  they 
are  often  soon  destroyed,  apparently  under  the  influence 
of  those  forms  naturally  present,  and  therefore,  better 
adapted  to  existing  conditions ;  but  this  is  by  no  means 
always  the  case,  some  of  the  more  virulent  pathogenic 
organisms  having  high  resisting  power. 

Max  Holz  (Zeit. /.  Hyg.,vm,  159)  gives  a  method  of 
preparing  a  potato-gelatin,  in  which  he  finds  the  typhoid 
bacillus  to  grow  freely.  If  such  a  culture  medium  be 
treated  with  0.05  per  cent,  of  pure  phenol,  it  is  found  that 
the  growth  of  moulds  and  liquefying  bacilli  is  prevented 
while  the  growth  of  the  B.  typhosus  is  merely  somewhat 
delayed. 


SANITARY   APPLICATIONS. 


97 


CULTURE    PHENOMENA  OF    SOME  OF   THE    MORE   IM- 
PORTANT MICROBES. 
Compiled  from  Mace  and  others. 


ACTION   ON 
GELATIN. 

ON  POTATO. 

RELATION 
TO  OXYGEN 

REMARKS 

Bacillus  butyricus,    . 

Liquefies. 

Anaerobe. 

Produces      butyric 

acid. 

Bacillus  chlorinus,      . 

Liquefies. 

Ae'robe. 

Produces    a    green 

color. 

Bacillus  coeruleus,  .    . 

Liquefies. 

Dark  bluish 

Aerobe. 

Produces  blue  color. 

film. 

BacillusoMtcom- 

munf1S* 

Does  not 

Yellowish- 

Ae'robe. 

Not     colored      by 

liquefy. 

green  film. 

Gram's  method. 

Bacillus  erythro- 
sporus,  

Does  not 

Reddish 

Ae'robe. 

liquefy. 

film. 

Bacillus  flavus,    .    .    . 

Liquefies. 

Ae'robe. 

Forms  a  yellowish 

deposit. 

Bacillus  fluorescens 

liquefaciens,     .    .    . 

Liquefies. 

Glistening 

Aerobe. 

Strong  green   fluo- 

yellow film. 

rescence. 

Bacillus  fluorescens 

putidus,    .       ... 

Does  not 

.    . 

Aerobe. 

Greenish    fluores- 

liquefy. 

cence. 

Bacillus  subtilis,     .    . 

Liquefies 

Cream-col'd 

Ae'robe. 

Occurs    in  hay  in- 

slowly. 

film. 

fusion. 

Bacillus  typhosus,  .    . 

Does  not 
liquefy. 

Thin,  glairy 
film,  harsh 

Facultative 
anaerobe. 

Not     colored      by 
Gram's  method  ; 

aud  resist- 

does     not     give 

ing. 

indol  reaction. 

Bacillus  violaceus,  .   . 

Liquefies 

Brownish 

Aerobe. 

Violet    color    pro- 

rapidly. 

film. 

duced  only  in  the 

presence  of  oxy- 

gen ;  reduces  ni- 

trates to  nitrites. 

Micrococcus  aquatilis, 

Does  not 

Aerobe. 

Colonies  white  and 

liquefy. 

crenate. 

Micrococcus  prodigio- 

sus 

Liquefies. 

Blood  red. 

Aerobe. 

Generally   intro- 

Old cultures 

duced    from    the 

have  green- 

air. 

ish  lustre. 

Spirillum  cholerae, 

Slowly 
liquefies. 

Grows  only 
at  moder- 

Obligatory 
ae'robe. 

Not    colored  by 
Gram's    method. 

ately  high 

Gives    indol     re- 

temperature, 

action. 

as  a  thin 

brownish 

film. 

Spirillum  Finkleri, 

Liquefies 
rather 

Grows  at  or- 
dinary   tem- 

Aerobe. 

Gives     indol    re- 
action feebly. 

rapidly. 

perature  as  a 

gray  film 

with  white 

ragged 

margin. 

98  PURIFICATION    OF   WATER. 


PURIFICATION  OF  DRINKING  WATER. 

The  most  obvious  method  of  purifying  water  is  by  dis- 
tillation. The  process  is  too  expensive  for  general  use,  but 
is  especially  adapted  for  water  intended  for  pharmaceutical 
or  chemical  purposes.  It  has  also  been  used  for  supplying 
vessels  at  sea  and  in  tropical  localities  in  which  the  natural 
waters  may  be  contaminated  with  malarial  or  other  germs. 
The  majority  of  microbes  are  killed  by  short  exposure  to  a 
temperature  of  212°  F. ;  hence,  water  may  be  purified,  on 
a  small  scale,  by  simple  boiling.  Freezing  does  not  have 
the  same  effect,  many  microbes  retaining  vitality  for  a  long 
while  in  ice. 

The  self-purification  of  water,  that  is  the  destruction  of 
organic  matter  and  pathogenic  microbes,  by  reason  of  the 
development  of  the  ordinary  microbes  of  putrefaction, 
occurs  satisfactorily  only  in  alkaline  waters,  hence,  acid 
effluents  check  this  process.  The  addition  of  lime  in  suffi- 
cient amount  to  give  a  slightly  alkaline  reaction  will  be 
beneficial. 

The  methods  in  general  use  for  purifying  water  are 
simple  filtration  and  the  removal  of  the  impurities  by  ap- 
propriate chemical  agents. 

Filtration. — For  household  purposes  forms  of  carbon, 
stone  and  sand  filters  are  used,  which  yield  clear  filtrates, 
but  permit,  sooner  or  later,  the  transmission  of  microbes. 
The  suspended  matter  in  the  water  gradually  accumulates 
on  the  surface  of  the  filter,  and  causes  a  great  increase  in 
the  number  of  the  microbes,  some  species  of  which  appar- 
ently grow  through  the  pores  of  the  filter,  and  are  carried 
into  the  filtrate.  The  following  are  among  the  more  ef- 
ficient forms  of  household  filters : — 


SANITARY   APPLICATIONS. 


99 


Bischof  Spongy- Iron  Filter. — The  construction  of  this  is 


shown  in  Fig.  13.  The  spongy  iron 
is  obtained  by  reducing  haematite, 
at  a  temperature  below  the  fusing 
point  of  iron. 

It  rests  on  a  layer  of  pyrolusite 
(manganese  dioxide),  below  which 
is  an  asbestos  bag  having  a  short 
tube  with  perforated  cap.  This  is  a 
very  efficient  form,  removing  much 
of  the  dissolved  organic 
matter,  and  practically 
all  the  suspended  matter, 
including  the  microbes. 
Chamberlain  -Pasteur 
filter. — This  consists  of 


FIG.  13. 


FIG.  14. 


FIG.  15. 


tubes  of  unglazed  biscuit-ware,  the  number 
depending  on  the  size  and  required  delivery  of 
the  filter.  Fig.  14  shows  the 
arrangement  for  continuous  fil- 
tration by  attaching  the  tube  to 
the  faucet.  Fig.  15  shows  a 

form  adapted  to  simultaneous  cooling  and 

filtration.    The  observations  of  Pasteur  and 

others   have  shown    that   this   is   a   highly 

efficient  filter,  yielding  for  a  considerable 

time  a  filtrate  entirely  sterile.     It  requires 

occasional  cleaning,  since,  after  continuous 

use,   the   microbes   may  pass   through  the 

pores,  probably  by  a   process  of  growth. 

An  occasional   boiling  of  the  tubes  in  water  would   be 

sufficient  to  overcome  this  difficulty. 


IOO 


PURIFICATION    OF   WATER. 


FIG. 16. 


Fig.  1 6  shows  a  form  of  sand  filter  which  is  used  in  the 
laboratory  of  Professor  Kemna,  at  Antwerp.  A  moder- 
ately wide  and  stout  tube  is 
passed  to  the  bottom  of  a 
tall  jar,  and  the  intervening 
space  filled  to  the  depth  of 
about  twenty-five  centime- 
ters with  fine  sand,coarse  sand 
and  gravel,  as  shown.  The 
exit  tube  consists  of  a  siphon, 
the  outer  leg  of  which  does 
not  quite  reach  to  the  level 
of  the  surface  of  the  sand, 
the  inner  leg  reaching  to  the 
bottom  of  the  jar.  The  flow 

may  be  controlled  by  a  stop-cock  attached  to  the  outer 
leg.  The  object  of  this  arrangement  is  to  prevent  the 
water  level  being  drawn  to  or  below  the  level  of  the  sand. 
The  filter  should  be  supplied  from  a  reservoir  by  means  of 
a  siphon,  the  exit  tube  of  which  is  curved  upward,  in 
order  to  prevent  disturbing  the  deposit  which  collects  on 
the  surface  of  the  filter. 

The  filter  may  be  cleaned  by  removing  the  siphon  and 
sending  a  slow  current  of  water  down  the  wide  tube  until 
the  deposit  upon  the  surface  of  the  sand  is  washed  out. 
The  apparatus  is  especially  suited  for  laboratory  experi- 
ments on  filtration. 

For  the  purification  of  drinking  water  on  a  large  scale, 
sand  filter  beds  have  been  found  to  be  efficient ;  but  the 
best  results  are  obtained  only  under  proper  supervision. 

Numerous  determinations  of  the  efficiency  of  sand  filter- 
ing basins  have  been  made  by  bacteriological  and  chemical 


SANITARY    APPLICATIONS: J  '  '    IOI 

methods.  It  has  been  found  that,  at  the  start,  a  large  pro- 
portion of  the  organic  matter,  dead  and  living,  passes 
through ;  but  that  as  filtration  proceeds,  the  surface  of  the 
sand  becomes  covered  with  a  close  deposit,  which  acts  both 
as  a  means  of  retaining  suspended  impurities  and,  by  its 
active  microbic  life,  destroys  the  organic  matter  in  a  man- 
ner analogous  to  that  occurring  in  soil.  The  water  thus 
becomes  practically  free  from  microbes,  but  after  a  time 
these  gradually  penetrate  the  pores  of  the  filter  and  appear 
in  the  filtrate.  Increase  of  pressure  will  hasten  this  effect. 

Bertschinger  (Jour.  Soc.  Chem.  Ind.,  Dec.  1889; 
abstract)  has  published  observations  on  the  efficiency  of 
the  sand  filters  in  use  at  the  Zurich  Public  Water-works. 
The  filtering  material  rests  on  a  brick  grating,  and  consists 
of  the  following  layers,  commencing  at  the  bottom  : — 

5  to  15  cm.  of  coarse  gravel,  10  cm.  of  garden  gravel, 
15  cm.  of  coarse  sand  and  80  centimeters  of  fine  sand. 
As  soon  as  the  diminution  in  pressure  of  water,  due  to  the 
resistance  of  the  filter,  is  from  60  to  80  cm.,  the  filter  is 
cleaned  by  allowing  the  water  to  run  off  and  removing  the 
top  layer  of  sand  to  a  depth  of  2  cm.,  as  this  is  found  to 
contain  the  whole  of  the  mud.  The  filter  is  then  filled 
up  with  filtered  water  from  below,  and  washed  by  allowing 
this  to  overflow.  After  filtration  has  recommenced,  the 
first  portion  of  the  filtrate  is  rejected.  Two  of  the  filters 
are  arched  over;  these  require  cleaning  once  in  seventy- 
seven  days  ;  the  others  once  in  forty-eight  days.  As  soon 
as  the  layer  of  fine  sand  has  been  reduced  to  the  thickness 
of  50  cm.,  fresh  sand  is  substituted  or  more  added,  until 
the  depth  is  again  80  cm.  Among  the  conclusions  reached 
are  the  following  : — 

Under  normal  conditions  the  filtered  water  is  free  from 


102  PURIFICATION   OF   WATER. 

microbes,  although  a  few  are  taken  up  again  in  the  later 
stages  of  the  filtration. 

After  cleaning  the  filter,  the  water  which  first  passes 
through  is  not  in  normal  condition.  It  contains  many 
microbes,  the  efficient  layer  of  scum  not  having  had  time  to 
collect  on  the  sand,  though  the  chemical  purity  of  the 
water  is  satisfactory. 

When  the  filters  have  not  been  used  for  some  time,  the 
water  which  first  passes  through  them  contains  more  bac- 
teria than  usual,  owing  to  their  rapid  multiplication  in 
stagnant  water,  but  its  chemical  purity  is  not  materially 
different  from  the  normal  filtered  water. 

Precipitation  Methods. — The  observations  of  Dr. 
P.  F.  Frankland  and  others,  have  established  the  following 
points : — 

"  Organized  matter  is,  to  a  large  and  sometimes  to  a  most 
remarkable  extent,  removable  from  water  by  agitation  with 
suitable  solids  in  a  fine  state  of  division,  but  such  methods 
of  purification  are  unreliable. 

"  Chemical  precipitation  is  attended  with  a  large  reduc- 
tion in  the  number  of  microorganisms  present  in  the  waters 
in  which  the  precipitate  is  made  to  form  and  allowed  to 
subside. 

"  If  subsidence  either  after  agitation  or  after  precipita- 
tion be  continued  too  long,  the  organisms  first  carried  down 
may  again  become  redistributed  throughout  the  water." 

It  is  essential,  therefore,  that  the  liquid  be  filtered  as 
short  a  time  after  the  precipitation  as  possible. 

A  small  quantity  of  alum  added  to  water  is  decom- 
posed with  the  formation  of  a  flocculent  precipitate  of  alu- 
minum hydroxide,  which  settles  comparatively  rapidly,  and 
carries  down  with  it  all  suspended  matters,  as  well  as  a  large 


SANITARY   APPLICATIONS.  103 

proportion  of  the  dissolved  organic  matters.  Waters  which 
contain  such  an  excess  of  organic  matter  as  to  be  distinctly 
colored,  may  usually  be  made  quite  clear  and  colorless  by 
this  treatment.  Two  grains  of  alum  to  the  gallon  will 
suffice  for  the  purpose,  but  if  very  rapid  subsidence  is  de- 
sired more  may  be  added. 

Several  systems  of  filtration  now  in  extended  use  employ 
this  precipitation  method  in  conjunction  with  filters  of  small 
area,  the  necessary  flow  being  obtained  by  increased  pres- 
sure. The  Hyatt  and  National  systems  belong  to  this 
class.  The  differences  between  the  various  forms  are  chiefly 
in  the  mechanical  arrangements  for  supplying  the  water 
and  for  cleaning  the  filter.  The  material  is  generally  sand 
or  coke  ;  the  cleaning  is  performed  at  short  intervals,  by 
means  of  reverse  currents  of  water.  The  alum  solution  is 
introduced  as  needed  by  automatic  apparatus. 

These  filters  are  efficient,  and  are  suitable  for  the  purifi- 
cation of  water  for  manufacturing  establishments,  and  when 
large  basins  are  not  available. 

The  addition  of  an  iron  salt  to  water  containing  carbon- 
ates, is  attended  with  decomposition  and  the  formation  of 
a  precipitate  of  ferric  hydroxide.  This  reaction  has  been 
employed  with  great  advantage  as  a  means  of  purification. 
One  of  these  methods  was  by  passing  the  water  through 
spongy  iron,  then  aerating  to  precipitate  the  iron,  and  filt- 
ering through  sand.  The  method  is  very  efficient,  but  the 
spongy  iron  gradually  chokes  by  oxidation,  and  becomes 
useless.  This  difficulty  is  removed  by  the  use  of  iron  bor- 
ings or  punchings,  contained  in  an  iron  cylinder  (Anderson 
and  Ogston,  Proc.  Inst.  Civ.  Eng.  Vol.  81),  which  is  rotated 
while  the  water  passes  through  ;  the  iron  is  brought  into 


104  PURIFICATION    OF   WATER. 

thorough  contact  with  the  water,  and  there  is  sufficient 
abrasion  to  keep  its  surface  clean. 

The  apparatus  as  practically  employed  is  shown  in  Fig. 
1 7.  It  consists  of  a  cylinder  rotating  in  a  horizontal  position, 
attached  to  the  internal  periphery  of  which  are  short  curved 
shelves,  arranged  at  equal  distances.  Pipes  enter  the  hollow 
trunnions  to  admit  and  discharge  the  water.  As  it  enters 
the  cylinder,  the  water  strikes  against  a  circular  distributing 
plate,  and  is  caused  to  flow  radially  through  a  narrow  an- 
nular space,  to  prevent  the  formation  of  a  central  current 
along  the  axis  of  the  purifier.  The  inner  end  of  the  out- 
let pipe  carries  an  inverted  bell-mouth  which  catches  the 
fine  particles  of  the  iron  carried  forward  by  the  water, 
and  causes  them  to  fall  again  to  the  bottom  of  the  cylinder. 
Sufficient  borings  or  punchings  to  one-tenth  fill  the 
cylinder  are  introduced,  and  the  purifier  is  then  completely 
filled  with  water,  and  set  in  motion,  the  rate  of  rotation 
being  about  six  feet  per  minute  at  the  periphery.  The 
effect  of  the  rotation  is  to  scoop  up  the  iron  particles  and 
to  shower  them  down  through  the  flowing  water. 

The  effect  is  due  mainly  to  the  formation  of  ferrous 
carbonate,  through  the  action  of  the  carbonic  acid  of  the 
water.  On  issuing  into  the  open  air,  this  is  gradually  con- 
verted by  oxidation  into  the  insoluble  ferric  hydroxide, 
which  carries  down  much  of  the  organic  matter  and  sub- 
sequently oxidizes  and  destroys  it.  Temporary  hardness 
is  also  decreased  by  the  abstraction  of  the  carbonic  acid 
and  consequent  precipitation  of  calcium  and  magnesium 
carbonates. 

The  time  of  contact  with  the  iron  depends  upon  the 
purity  of  the  water.  For  Antwerp  water,  which  is  purified 
by  this  means,  the  maximum  effect  is  accomplished  in  3.5 


106  PURIFICATION    OF   WATER. 

minutes.  After  leaving  the  cylinder,  the  water  is  passed 
through  sand  filters.  Analytical  examinations  show  the  efflu- 
ent water  to  be  of  high  organic  purity  and  practically  sterile. 

Cast-iron  borings  are  much  more  readily  acted  upon 
than  steel  punchings.  The  latter  suffice  in  operating  upon 
water  rich  in  dissolved  organic  substances,  carbon  dioxide 
and  suspended  matters,  while  the  former  are  especially 
suited  for  treatment  of  water  comparatively  pure,  and, 
therefore,  less  active. 

For  determining  the  most  advantageous  method  of  treat- 
ing any  water  supply,  laboratory  experiments  may  be  made 
as  follows : — 

A  strong  wide-mouth  bottle  holding  about  2000  c.  c.,  is 
charged  with  one-tenth  its  bulk  of  clean  borings  or  punch- 
ings, filled  completely  with  water  and  shaken  for  four  min- 
utes, in  such  manner  that  the  iron  particles  are  continuously 
showered  through  the  liquid.  The  water  is  then  aerated 
by  agitating  it  in  a  large,  thoroughly  clean  glass-stoppered 
bottle.  With  some  (e.g.,  peaty)  waters,  it  will  be  of 
advantage  to  allow  about  200  c.  c.  of  air  to  remain  in  the 
bottle  in  which  the  shaking  with  iron  is  performed,  occa- 
sionally removing  the  stopper  to  renew  the  air.  (Con- 
tinuous aeration  during  treatment  is  provided  for  in  the 
apparatus  used  on  the  large  scale).  The  liquid  is  allowed 
to  stand  from  a  few  minutes  to  four  hours,  depending  on  the 
rapidity  with  which  the  iron  separates,  and  is  then  filtered 
through  the  sand  filter  (page  100),  or  through  a  well- 
washed  cotton  plug  inserted  in  the  neck  of  a  funnel.  Sat- 
isfactory purification  as  regards  ammonium  compounds 
cannot  be  obtained,  but  with  proper  attention  to  cleanliness, 
the  figures  for  total  organic  nitrogen,  nitrogen  by  perman- 
ganate, and  oxygen  consuming  power  will  be  trustworthy. 


SANITARY   APPLICATIONS.  107 

The  following  results  were  obtained  by  us  in  the  treatment 
of  Delaware  river  water  at  Lardner's  Point  pumping 
station,  Philadelphia.  The  purifier  was  capable  of  deliver- 
ing 100,000  gallons  per  24  hours.  All  figures  are  in  parts 
per  million. 

September,  1890. 

Before  Treatment.     After  Treatment. 
Nitrogen  as  ammonium,  .04  .03 

"         as  permanganate,          .27  .09 

November,  1890. 

Nitrogen  as  ammonium,  .084  .034 

"         by  permanganate,         .091  .049 

"         as  nitrites,  traces.  none. 

A  sample  of  Schuylkill  water  treated  in  the  laboratory, 
and  the  reduction  of  total  organic  nitrogen  determined, 
gave  the  following  figures  : — 

Before  Treatment.    After  Treatment. 
Total  organic  nitrogen,  0.36  0.118. 

Sample  of  water  from  the  Mississippi  river  at  Memphis 
Tenn. 

Before  Treatment.     After  Treatment. 
Oxygen  absorbed  at  2I2°F.,       2.88  0.36 

IDENTIFICATION  OF  THE  SOURCE  OF  WATER. 

The  determination  of  the  course  of  underground  streams, 
and  of  communications  between  collections  of  water,  is 
often  an  important  practical  problem.  In  geological  and 
sanitary  surveys,  valuable  information  may  occasionally  be 
gained.  The  method  generally  pursued  when  connection 
between  water  at  accessible  points  is  to  be  detected,  is  to 
introduce  at  one  point  some  substance  not  naturally  exist- 
ing in  the  water,  and  capable  of  recognition  in  small 


108  IDENTIFICATION    OF   SOURCE. 

amount.  Lithium  compounds  are  among  the  best  for  this 
purpose.  They  are  not  frequent  ingredients  of  natural 
waters,  and  are  easily  recognized  by  the  spectroscope. 
Lithium  chloride  is  the  most  suitable.  The  quantity  to  be 
employed  will  vary  with  circumstances.  It  scarcely  needs 
to  be  stated  that  the  waters  under  examination  should  be 
carefully  tested  for  lithium  before  using  the  method. 

When  the  lithium  method  is  inadmissible,  recourse  must 
be  had  to  other  substances  of  distinct  character,  such  as 
strontium  chloride,  but  this  possesses  the  disadvantage  that 
a  considerable  amount  may  be  rendered  insoluble,  and  thus 
lost  in  the  ordinary  transit  through  soil.  Recently,  use  has 
been  made  of  organic  coloring  matters  of  high  tinctorial 
power,  one  of  the  most  suitable  of  which  is  fluoresce'in, 
C20H12O5,  a  derivative  of  benzene.  This  will  communicate 
a  characteristic  and  intense  fluorescence  to  many  thousand 
times  its  weight  of  water.  An  entire  river  may  be  colored 
by  a  few  kilograms.  By  its  use  an  underground  communi- 
cation was  demonstrated  to  exist  between  the  Danube  and 
the  Ach,  a  small  river  which  flows  into  the  Lake  of  Con- 
stance. The  coloration  is  only  distinct  in  alkaline  liquids. 
Other  colors,  such  as  aniline  red,  may  be  employed.  For 
detecting  leakage  from  cesspools  and  cisterns,  sanitary 
inspectors  occasionally  employ  water  colored  by  Prussian 
blue. 

A  more  important  feature  of  the  problem  in  a  sanitary 
point  of  view  is  the  determination  of  the  source  of  a  given 
current  or  collection  of  water,  when  such  source  is  inaccessi- 
ble. Problems  of  this  character  are  not  infrequent  in  large 
cities  in  which  the  systems  of  water  supply  and  drainage  are 
defective,  thus  giving  occasion  to  accumulations  of  water 
in  cellars  and  similar  places.  Often,  in  these  cases,  no  ex- 


SANITARY  APPLICATIONS.  1 09 

tended  explorations  can  be  made,  by  reason  of  the  adjacent 
buildings  and  conflicting  property  interests,  and  the  ques- 
tion may  arise  whether  the  water  proceeds  from  a  leaky  hy- 
drant, drain,  sewer,  or  subsoil  current.  It  is  obvious  that 
in  the  case  of  the  collection  of  water  in  a  cellar  from  causes 
other  than  surface  washings  or  entrance  of  rain,  it  must 
have  passed  through  some  distance  of  soil,  and  in  built-up 
districts  will  almost  certainly  be  charged  with  organic 
refuse.  To  correctly  interpret  the  results,  it  will  be  neces- 
sary to  know  the  general  character  of  the  subsoil  water  of 
the  district  and  the  composition  of  the  public  supply.  As 
a  rule,  the  transmission  of  water  through  moderate  distances 
of  soil  will  not  materially  increase  the  mineral  constituents. 
Hence,  if  the  sample  contains  an  excess  of  dissolved  mat- 
ters as  compared  with  the  water  supply  of  the  district,  it 
may  reasonably  be  inferred  that  it  is  derived  from  a  drain, 
sewer,  or  subsoil  current. 

In  these  investigations  it  will  generally  be  sufficient  to 
determine  the  total  solids,  odor  on  heating,  chlorine, 
nitrates  and  nitrites.  The  following  figures  are  from  some 
results  obtained  in  investigations  made  in  association  with 
Mr.  Chas.  F.  Kennedy,  Chief  Inspector  to  the  Board  of 
Health  of  this  city  :— 


CELLAR    WATER. 


CITY   SUPPLY. 

No.  i. 

No.  2. 

No.  3. 

Total  solids,  .  .    . 

.   .    "5 

140 

66  1 

640 

Odor  on  heating,  . 

.    .  faint 

faint 

strong 

urinous 

Chlorine,  .... 

4 

6.4 

77.0 

128.0 

N  as  nitrates,   .    . 

0.7 

i.o 

3.5 

none 

"    "  nitrites,    .    . 

.    .   none 

present 

present 

none 

Sample  No.  i  was  taken  from  a  cellar  in  which  a  small 
amount  of  water  had  been  almost  constantly  present  for  a 


110  IDENTIFICATION    OF    SOURCE. 

long  time,  and  of  which  the  source  could  not  be  ascertained. 
The  results  of  analysis  led  to  the  view  that  since  it  resem- 
bled in  composition  the  city  supply,  it  was  derived  from  a 
leaky  hydrant  pipe.  The  parties  in  interest  were  not  in- 
clined to  accept  this  opinion,  but  the  examination  of  the 
condition  of  the  hydrant  on  an  adjacent  property  showed 
a  leak,  which  being  repaired  the  water  ceased  to  appear  in 
the  cellar.  In  this  case  it  was  found  that  the  water  had 
passed  through  twenty-two  feet  of  earth.  In  the  second  case 
the  sample  is  seen  to  be  very  impure,  and  it  was  suggested 
that  it  was  derived  directly  from  a  leaky  drain,  which  upon 
exploration  proved  to  be  the  case.  In  the  third  sample,  the 
high  chlorine^  strong  urinous  odor  and  absence  of  nitrates 
and  nitrites  pointed  unmistakably  to  recent  and  profuse 
contamination  with  sewer  water. 

Occasionally  the  analytical  results  will  be  ambiguous,  and 
it  is  advisable  to  make  examinations  of  more  than  one 
sample,  since  accidental  circumstances,  rain-fall,  etc.,  may 
affect  the  composition  of  the  water. 

Instances  of  the  contamination  of  water  by  unusual  sub- 
stances are  occasionally  noted,  and  these  sometimes  afford 
a  clue  to  the  source  of  the  water.  Among  the  instances 
of  this  kind  within  our  own  experience  may  be  noted  the 
contamination  with  petroleum  and  with  soap.  In  the 
former  case  it  was  evident  that  the  contamination  was  from 
a  leaky  pipe  connecting  two  refineries.  In  the  latter  it 
was  shown  to  be  derived  from  an  adjoining  building  used 
as  a  laundry. 


TECHNICAL   APPLICATIONS.  Ill 

TECHNICAL  APPLICATIONS. 

Boiler  Waters. — The  main  conditions  affecting  the 
value  of  a  water  for  steam  making  purposes  are  its  tendency 
to  cause  corrosion  and  the  formation  of  scale.  Corrosion 
may  be  due  to  the  water  itself,  to  the  presence  of  free  acids, 
or  to  substances  which  form  acids  under  the  influence  of 
the  heat  to  which  the  water  is  subjected.  Pure  water,  e.g., 
distilled  water,  exhibits  a  powerfully  corrosive  action  upon 
iron.  The  dissolved  oxygen  which  all  waters  contain  also 
aids  in  the  corrosion,  and  especially  when  accompanied,  as 
is  usually  the  case,  by  carbonic  acid.  There  is  always 
greater  rusting  at  the  point  at  which  the  water  enters  the 
boiler,  since  there  the  gases  are  driven  out  of  solution  and 
immediately  attack  the  metal.  This  is  an  evil  that  obtains 
with  all  waters,  and  it  is  not  customary,  in  making  examina- 
tion for  technical  purposes,  to  determine  the  amount  of 
these  bodies.  In  water  that  has  had  free  access  to  air,  the 
oxygen  in  solution  is  a  tolerably  constant  quantity,  and  it 
is  sufficient  to  note  the  temperature  and  refer  to  the  table 
of  amounts  of  oxygen  dissolved  in  water.  The  corro- 
sive action  of  oxygen  and  carbonic  acid  is  especially 
noticeable  in  waters  that  are  comparatively  pure,  such  as 
those  derived  from  mountain  springs.  This  was  repeatedly 
observed  by  one  of  us  in  the  examination  of  the  waters 
used  for  the  locomotives  of  the  Baltimore  and  Ohio  railroad. 
The  waters  which  caused  the  most  corrosion  were  mainly 
those  containing  small  quantities  of  solid  matter,  the  full 
amount  of  oxygen  and  considerable  carbonic  acid,  but  no 
other  acid  or  acid-  forming  body. 

Free  acid,  other  than  carbonic  acid,  is  not  often  found 
in  water,  and  if  present  renders  the  water  unfit  for  use, 


112  BOILER   WATERS. 

unless  it  be  neutralized.  Mine  waters  are  the  most  likely 
to  contain  free  acid,  sulphuric  acid  being  generally  present. 
Sometimes  the  acidity  is  due  to  organic  acids.  These  act 
very  injuriously  on  iron.  Allen  gives  an  example  of  this 
in  the  water  supplied  to  Sheffield,  Eng.,  which  he  found 
to  contain  an  organic  acid  in  amount  equivalent  to  from 
3.5  to  10  parts  of  sulphuric  acid  per  million. 

Magnesium  chloride  is  frequently  present  in  waters,  and 
if  in  considerable  quantity  may  be  very  harmful.  At  a  tem- 
perature of  310°  F.,  corresponding  to  an  effective  pressure 
of  four  atmospheres/magnesium  chloride  reacts  with  water 
to  form  magnesium  oxide  and  hydrochloric  acid,  the 
latter  attacking  the  boiler,  especially  at  the  water  line.  If 
there  is  present  at  the  same  time  considerable  calcium 
carbonate  the  evil  may  be  somewhat  lessened,  but  as 
Allen  has  pointed  out,  and  as  we  also  have  noticed,  there 
may  still  be  corrosion,  so  that  the  presence  of  more  than  a 
small  quantity  of  the  salt,  say  a  grain  or  two  to  the  gallon, 
may  be  considered  objectionable.  Allen  remarks  that  the 
presence  of  a  certain  amount  of  sodium  chloride  may 
prevent  this  decomposition,  the  two  chlorides  combining 
to  form  a  stable  double  salt.  The  addition,  therefore,  of 
common  salt  to  a  water  containing  magnesium  chloride 
may  act  to  diminish  corrosion,  a  point  which  will  bear 
further  investigation. 

It  has  not  been  determined  how  far  the  presence  of 
nitrites,  nitrates  and  ammonia  affects  the  quality  of  water 
for  steam-making  purposes ;  but  it  is  more  than  probable 
that  they  act  harmfully,  especially  the  nitrates,  which  are 
frequently  present  in  large  amount. 

Scale  is  composed  of  matters  deposited  from  the  water 
either  by  the  decompositions  induced  by  the  heat  or  by 


TECHNICAL   APPLICATIONS.  113 

concentration.  When  the  deposit  is  loose  it  is  termed 
sludge  or  mud,  and  usually  consists  of  calcium  carbonate, 
magnesium  oxide  and  a  small  amount  of  magnesium  car- 
bonate. The  magnesium  oxide  is  formed  by  the  decompo- 
sition of  the  magnesium  carbonate  and  chloride.  This 
fact  was  first  pointed  out  by  Driffield  (/".  Soc.  Chem.  Ind., 
vi,  178). 

The  formation  of  sludge  is  the  least  objectionable  effect, 
since  it  may  readily  be  removed  by  "  blowing  off,"  pro- 
vided that  care  is  previously  taken  to  allow  the  flues  to 
cool  down  so  that  when  the  water  is  removed  the  heat  of 
the  flues  may  not  bake  the  deposit  to  a  hard  mass.  Waters 
containing  calcium  sulphate  form  hard  incrustations  diffi- 
cult to  remove  and  causing  great  loss  of  fuel  by  inter- 
fering with  the  transmission  of  the  heat  to  the  water.  It 
not  only  forms  a  hard  incrustation  in  itself,  but  becomes 
incorporated  with  the  mud  and  renders  it  also  hard.  The 
hard  scale  will  also  contain  practically  all  the  silica  and 
the  iron  and  aluminum  present  in  the  water,  besides  any 
matters  originally  held  in  suspension. 

It  follows  from  the  -above  that  a  water  only  temporarily 
hard,  will,  if  care  is  taken  in  the  management  of  the  boiler, 
cause  the  formation  merely  of  a  loose  deposit  of  sludge — 
temporary  hardness  being  due  in  the  main  to  calcium  and 
magnesium  carbonates.  A  water  permanently  hard  will 
probably  form  a  hard  scale,  since  such  hardness  is  usually 
due  to  calcium  sulphate. 

In  accordance  with  these  principles,  the  analysis  of  a 
water  for  steam-making  purposes  may  include  the  determi- 
nations of  free  acid,  total  solid  residue,  SO4,  Cl,  Ca,  Mg, 
temporary  and  permanent  hardness.  In  cases  in  which  the 
qualitative  tests  show  but  small  amounts  of  SO4  and  Cl, 


114  BOILER   WATERS. 

the  analysis  may  be  limited  to  the  determinations  of  the 
temporary  and  permanent  hardness. 

It  has  been  pointed  out  in  an  earlier  chapter  that  it  is 
not  possible  to  deduce  from  the  analytical  result  the  exact 
forms  in  which  the  various  elements  are  combined,  but 
since  it  is  known  that  at  the  high  temperature  ordinarily 
reached  in  boilers  definite  chemical  changes  occur,  it  is 
safest  to  exhibit  the  maximum  amount  of  corrosive  and 
scale-forming  ingredients  which  the  water  under  these  cir- 
cumstances could  develop.  Thus,  since  calcium  sulphate 
is  practically  insoluble  in  water  above  212°  F.,  the  pro- 
portion of  calcium  sulphate  may  be  regarded  as  such  as 
would  be  formed  by  the  total  quantity  of  calcium  or  the 
total  quantity  of  SO4,  according  to  which  is  present  in  the 
larger  amount.  Similarly,  as  the  decomposition  of  magne- 
sium chloride  is  induced  by  the  high  temperature  of  the 
boiler,  the  analytical  statement  should  indicate  the  maxi- 
mum proportion  of  this  compound  obtainable  from  the 
magnesium  and  chlorine  present.  These  rules  cannot  ap- 
ply absolutely  to  waters  rich  in  alkali  carbonates,  since 
these  would  neutralize  any  acid  formed  from  the  magnesium 
chloride,  or  even  prevent  its  formation,  and  would  prevent 
to  a  large  extent  the  formation  of  calcium  sulphate.  Much 
remains  to  be  determined  concerning  the  effects  of  the 
high  temperature  and  concentration  to  which  boiler  waters 
are  subjected. 

Purification  of  Boiler  Waters. — The  problems  pre- 
sent in  the  treatment  of  boiler  waters  are  usually  the 
removal  of  the  calcium  carbonate  and  sulphate,  and  mag- 
nesium carbonate  and  chloride.  Both  carbonates  are 
appreciably  soluble  in  pure  water.  About  one  grain  of 
calcium  carbonate  to  the  gallon  is  usually  stated  to  be  the 


TECHNICAL  APPLICATIONS.  115 

proportion  dissolved,  but  it  has  been  pointed  out  by  Allen 
that  solutions  can  be  obtained  containing  twice  this  amount. 
If  the  water  contains  carbonic  acid  it  will  take  up  a  much 
greater  proportion  of  the  carbonates,  but  in  this  case  they  will 
be  deposited  from  the  solution  by  boiling.  This  has  been  ac-  - 
counted  for  by  supposing  the  existence  of  soluble  bicarbon- 
ates,  which  are  decomposed  by  the  boiling.  Nearly  all  of 
these  carbonates  can  be  thrown  out  of  solution  by  any  means 
that  will  deprive  the  water  of  the  carbonic  acid.  Sodium 
hydroxide  is  usually  the  best  for  the  purpose,  and  should 
be  added  in  quantity  just  sufficient  to  form  normal  sodium 
carbonate.  If  there  are  present  in  the  water  calcium  and 
magnesium  chlorides  and  sulphates,  these  also  will  be  de- 
composed and  precipitated  by  the  sodium  carbonate  so 
formed.  If  the  amount  of  sodium  carbonate  formed  is  not 
sufficient  to  decompose  all  of  these  bodies,  a  sufficient 
quantity  should  be  added  with  the  sodium  hydroxide  to 
effect  the  complete  decomposition.  The  precipitate  is 
allowed  to  settle  or  filtered  off. 

In  cases  in  which  the  feed- water  is  heated  before  it  enters 
the  boiler,  it  may  only  be  necessary  to  add  to  the  water 
sodium  carbonate  in  quantity  sufficient  to  decompose  the 
calcium  and  magnesium  chlorides  and  sulphates,  since  the 
heat  alone  will  suffice  to  throw  down  the  carbonates. 

Care  should  be  taken  in  these  precipitations  that  no 
more  sodium  hydroxide  is  added  than  is  required  for  the 
precipitation,  since  any  excess  would  tend  to  corrode  the 
boiler. 

Clark' 's  process  consists  in  treating  the  water  with  calcium 
hydroxide  (lime-water).  This  precipitates  the  calcium  and 
magnesium  carbonates  by  depriving  the  water  of  its  free 
carbonic  acid.  It  has,  of  course,  no  effect  upon  the  cal- 


Il6  BOILER   WATERS. 

cium  sulphate.  It  is  to  be  noted  that  the  proportion  of 
calcium  hydroxide  which  is  to  be  added  must  be  calculated 
from  the  amount  of  free  carbonic  acid  existing  in  the 
water,  and  not  from  the  amount  of  carbonates  to  be  re- 
moved. The  precipitate  will  usually  require  at  least  twelve 
hours  for  complete  subsidence,  but  after  three  or  four  hours 
the  water  will  be  sufficiently  clear  for  some  purposes.  If  a 
filter  press  is  used,  as  in  Porter's  process,  the  time  required 
for  clarification  is  very  much  shortened.  Another  advan- 
tage of  this  process  is  the  use  of  a  solution  of  silver  nitrate, 
in  order  to  determine  more  conveniently  the  proportion  of 
calcium  hydroxide  which  is  to  be  employed.  The  lime  is 
first  slaked  and  dissolved  in  water,  and  the  water  to  be 
softened  run  in  and  thoroughly  mixed  with  it.  From  time 
to  time  small  portions  are  taken  out  and  a  few  drops  of  a 
solution  of  silver  nitrate  added.  As  long  as  the  lime  is  in 
excess  a  brownish  coloration  is  produced.  When  this  has 
become  quite  faint,  and  just  about  to  disappear,  the  addi- 
tion of  the  water  is  discontinued,  and,  after  a  short  time, 
the  water  is  filtered  by  means  of  the  press. 

Soluble  phosphates  added  to  a  water,  precipitate  com- 
pletely in  a  flocculent  condition  any  calcium,  magnesium, 
iron  or  aluminum.  This  reaction  can  be  best  applied  by 
using  the  tri-sodium  phosphate  (Na3PO4  -f-  i2H2O),  which 
is  now  a  commercial  article.  By  reason  of  the  facility 
with  which  this  substance  loses  a  portion  of  its  sodium  to 
acids,  it  acts  not  only  as  a  precipitant  to  the  above  mate- 
rials, but  will  neutralize  any  free  mineral  acid  present  in  the 
water.  From  evidence  submitted  by  those  who  have  used 
the  process  on  the  large  scale,  it  appears  that  not  only  is 
no  hard  scale  formed,  but  that  scale  already  existing  prior 


TECHNICAL   APPLICATIONS.  II 7 

to  its  use  is  gradually  disintegrated  and  removed  with  the 
sludge.  Experiments  indicate  that  no  injury  results  from 
an  excess  of  the  material ;  but  the  economical  employment 
of  the  method,  especially  with  very  hard  waters,  can  only 
be  based  upon  a  correct  analysis,  and  an  estimation  of  the 
phosphate  required  for  the  precipitation.  In  many  cases 
the  composition  of  the  water  will  be  such  that  a  partial 
precipitation  will  be  sufficient. 

Waters  rich  in  ferrous  compounds  may  be  purified  by 
thorough  aeration  and  filtration,  the  iron  being  separated 
as  ferric  hydroxide.  Simple  filtration  through  a  bed  of 
manganese  dioxide  will  accomplish  the  same  purpose. 

General  Technical  Uses. — In  regard  to  the  quality 
of  water  for  technical  other  than  steam-making  purposes, 
such  as  brewing,  dyeing,  tanning,  etc.,  no  detailed 
methods  or  standards  can  be  laid  down.  The  nearest 
approach  to  purity  that  can  be  secured  in  the  supply  will 
be  of  the  greatest  advantage.  The  more  objectionable 
qualities  will  be  large  proportion  of  organic  matter,  espe- 
cially if  it  distinctly  colors  the  water,  excessive  hardness, 
and  notable  amounts  of  iron  or  free  mineral  acid.  It  is 
stated  by  Bell  {Jour.  Soc.  Chem.,  Ind.~}  that  one  part  per 
million  of  iron  will  render  water  unsuitable  for  bleaching 
establishments.  It  has  been  noted  that  a  large  proportion 
of  active  microbes  is  injurious  in  the  manufacture  of  indigo. 
In  artificial  ice  making,  a  very  pure  water  must  be  used  if 
a  clear  and  colorless  product  be  desired.  Any  suspended 
or  dissolved  coloring  matter  will  be  concentrated  by  the 
freezing  and  appear  in  the  bottom  or  centre  of  the  mass. 
The  Antwerp  water,  purified  by  the  Anderson  process,  is 


Il8  SEWAGE    EFFLUENTS. 

used  with  entire  satisfaction  for  the  manufacture  of  artificial 
ice  in  that  city. 

The  examination  of  sewage  effluents  and  waste  waters 
from  manufacturing  establishments  is  to  be  conducted  upon 
the  same  principles  as  for  ordinary  supplies,  but  especial 
attention  must  be  given  to  the  presence  of  poisonous 
metals,  and  free  mineral  acids.  The  latter  interfere  with 
the  normal  self-purification  of  the  water.  For  the  nitrogen 
determination,  the  Kjeldahl  process  will  be  found  more 
satisfactory  than  that  by  alkaline  permanganate. 


ANALYTICAL  DATA. 


i-*^  FACTORS  FOR  CALCULATION. 

Parts  per  100,000  X  -7  —  Grains  per  Imperial  Gallon 

"      "  1,000,000  X  -°7  =       "        "          "            " 

"      "  100,000  X  -583  =       "       "      U.  S.         " 

"      "  1,000,000  X  -058  =       "        "         "           " 

"      "     1,000,000       X  -ooSgft  =  Av.  pounds  per  1000  U.  S.  Gal. 

% 
Grains"    Imp.  gallon    H-  .7  =  Parts  per      100,000 

"  "  "  "  -r-  .07  —  "  "  1,000,000 
"  "  U.  S.  "  -r-  .583  =  "  "  100,000 
"  "  "  "  -H  .058  =  "  "  1,000,000 

A1203, X  -534  =  Al 

AgCl, ^    .X  -2473  =  Cl 

BaSO4,      X  -588        =  Ba 

BaS04, .    .X  -1373  -  S 

BaSO4,      X  -412  =  SO4 

B203, X  .3H3  =  B 

CaO, X  .7H3  =  Ca 

CaCO3,      X  -40  =  Ca 

Fe,08, X  -7  =  Fe 

KC1,      X  -524  -  K 

Mg2P2O7, X  -2162  =  Mg 

Mg2P207, X  -856  =  P04 

MnS, X  -632  =  Mn 

NaCl, X  -394  =  Na. 


120 


CONVERSION   TABLE. 


CONVERSION  TABLE. 


PARTS 
PER 
MILLION. 

GRAINS  PER 
U.    S.   GALLON. 

GRAINS 
PER 
IMP.  GAL. 

PARTS 
PER 
MILLION. 

GRAINS  PER 
U.   S.   GALLON. 

GRAINS 
PER 
IMP.  GAL. 

j 

.058 

.07 

26 

.508 

1.82 

2 

.116 

.14 

27 

.566 

1.89 

3 

.174 

.21 

28 

.624 

1.96 

4 

.232 

.28 

29 

.682 

2.03 

5 

.290 

•35 

30 

.740 

2.10 

6 

.348 

.42 

31 

.798 

2.17 

7 

.406 

49 

32 

.856 

2.24 

8 

.464 

.56 

33 

I.9H 

2.31 

9 

.522 

•63 

34 

1.972 

2.38 

10 

.580 

.70 

35 

2.030 

2-45 

ii 

.638 

•77 

36 

2.088 

2.52 

12 

.696 

.84 

37 

2.146 

2-59 

*3 

•754 

.91 

38 

2.2O4 

2.66 

H 

.812 

.98 

39 

2.262 

2-73 

15 

.870 

.04 

40 

2.320 

2.80 

16 

.928 

.12 

4i 

2.378 

2.87 

17 

.986 

.19 

42 

2.436 

2-94 

18 

.044 

.26 

43 

2.494 

3.01 

19 

.102 

•33 

44 

2.552 

3.08 

20 

.160 

.40 

45 

3.6lO 

3-15 

21 

.218 

•47 

46- 

2.668 

3.22 

22 

.276 

•54 

47 

2.726 

3-29 

23 

•334 

.61 

48 

2.784 

3.36 

24 

•392 

.68 

49 

2.842 

3-43 

25 

.450 

•75 

50 

2.900 

3-50 

TABLE    OF   DISSOLVED    OXYGEN.  121 


DIBDIN'S  TABLE  OF  OXYGEN  DISSOLVED  BY  WATER  AT  VARIOUS 

TEMPERATURES,  EXTENDED  TO  GIVE  THE  WEIGHT  OF  OXYGEN 

PER  LITER.     CORRECTED  TO  o°  C.  AND  76omm.  PRESSURE. 


CUBIC   INCHES   OF 

MILLIGRAMS 

TEMPERATURE 

TEMPERATURE 

OXYGEN    PER    GALLON 

OP   OXYGEN 

FAHRENHEIT. 

CENTIGRADE. 

(70000  GRAINS). 

PER    LITER. 

41°     ... 

.       .       .       5-00°    .       - 

.     .     .  2.IOI   .... 

.       .    10.84 

42       ... 

.   ...    5-55   .   . 

.     .     .  2.074  .... 

.       .    10.72 

43    ... 

.    6.ii    .    . 

.     .     .   2.048  .... 

.       -     10.57 

44    ... 

.    .    .    6.66 

.     .     .  2.022  .... 

•       •    10.45 

45    ... 

...    7-22    .    . 

.     .     .   1-997  .... 

.       .    10.30 

46    ... 

.    .   .    7-77   .    . 

.   .    .  1-973  .... 

.    .  10.18 

47    ... 

.    .    .    8.33   .    . 

.    .    .  1.949  .   .    .    . 

.    .  10.06 

48    ... 

.    .    .    8.89   .    . 

.    .    .  1.927  .... 

.    .    9-94 

49    ... 

.    .    .    9-44   .    . 

.    .    .  1.905  .... 

.    .    9-83 

50..    .. 

.     .     .    IO.OO 

.   .    .  1.884  .... 

.    .    9-72 

51     ... 

.  .  .  10.55  .  . 

.    .   .  1.864  .... 

.    .    9.61 

52    ... 

.    .    .11.11    .    . 

.    .    .  1-844  .... 

.    •    9-51 

53    ... 

.    .    .  11.66 

.    .    .  1.826  . 

.    .    9-42 

54    ... 

.     .     .   12.22    .     . 

.    .    .  1.808  .... 

.    .    9-33 

55    ... 

.     .     .    12.77     .     . 

.    .    .  i.79i  .    .    .    . 

.    .    9-24 

56    ... 

.     .     •   13-33     .     • 

.    .    .  1-775  .... 

.    .    9-15 

57    ... 

.     .     .   I3-89     .     . 

.    .    .  1.760  .... 

.   .    9.08 

58    ... 

.     .     .   14-44     .     • 

.    .    .  1.746  .... 

.    .    9.01 

59    ... 

.     .     .    I5.OO    .     . 

.    .    .  1.732  .... 

.   .    8.94 

60    ... 

.     .     .   15-55     -     . 

.    .    .  1.719  .... 

.    .    8.87 

61    .    .    . 

.    .    .  i6.n 

.    .    .  1.706  .... 

.   .    8.80 

62    ... 

.    .    .  16.66 

.    .    .  1.695  .... 

.   .    8.74 

63    ... 

•    •    •  17-22    .    . 

.    .    .  1.683  .... 

.    .    8.68 

64    ... 

.    .    .  17-77    •    • 

...  1.674  .    .    .    . 

.    .    8.64 

65    ... 

.    .    .  18.33    •    . 

.    .    .  1.667  .    .    . 

.    .    8.60 

66    ... 

.    .    .  18.89 

.    .  1.660  . 

.    .    8.56 

67    ... 

.    .    .  19-44    .    . 

.    .    .  1.652  .... 

.    .    8.52 

68    ... 

.    .    .  20.00 

,    .    .  1.644  .... 

.    .    8.48 

69    ... 

.    .    .  20.55    .    . 

.    .    .  1.639  .... 

.    .    8.45 

70    ... 

.     .     .  21.  II     .     . 

.    .   .  1.634  .... 

.    .    8.43 

The  table  is  calculated  for  a  barometric  pressure  of  760  mm.,  and  would  require 
corrections  for  variations  from  this,  but  such  corrections  are  mostly  within  the 
limits  of  experimental  error. 


122 


ANALYSES   OF   RAIN   AND    SUBSOIL   WATERS. 


ANALYSES  OF  RAIN  AND  SUBSOIL  WATERS. 

PARTS   PER  MILLION. 


* 

, 

O 

From. 

:i 
1 

1 

B 

9 

g 

o" 

fe 

g 

"rt 
£ 

| 

£ 

rt 

1 

• 

C5 

H 

5 

& 

fc 

fe 

K 

Bellefonte—  collected  by 

Rain  water. 

Prof.   Wm.    Frear,    after 
long  rain. 

5 

none 

0.148 

0.280 

none 

none 

Subsoil  water. 

Wynnewood  —  pool  fed 
by  underground  spring. 
Wynnewood  —  well  about 
150  yards  from  above. 

65 
60 

6.  20 
4.00 

0.032 
0.024 

0.024 
0.016 

none 
none 

2-3 
3-5 

Wynnewood  —  well    pol- 

«          « 

luted  by  farm-yard  drain- 
age ;  about  500  yards  from 

1  6.00 

0.208 

0.028 

none 

14.2 

pool. 

Pump  -  well    in  densely 

<«           it 

populated  district.  Highly 

II2O 

57.00 

I.OO 

3.120 

O.OI 

33-o 

contaminated. 

Newly  dug  well  in  popu- 

14                      ft 

lated  district.  Highly  con- 

620 

120.00 

0.08 

2.00 

0.03 

16  o 

taminated. 

It                       tt 

Well  at  Barren  Hill,  130 
feet  deep. 

470 

1  2O.OO 

undet. 

undet. 

traces 

22.0 

RESULTS    FROM    SCHUYLKILL   RIVER. 


123 


C     jj 

|g 

1?    ^MS>^J?MIMICM<S    ^RS.i-ScSR.w^R.R.R. 

(5  rt 

c    • 

0           0 

Sod' 

e          8  a  S  fi  8 

o 

o      "      gtJo^o"*     "       "      ----»-•»»-- 

t—  1 

gs 

3     'a 

H      % 

C3     • 

HE 

00           O-*i                                        g                   OON«VOOO(SWOOOOOO 

*^-            N          Q^^^^^M         C            V             OMCMOMMOOMM 

o       o     So-"        ^0°     "      ooooooooooo 

gS 

55                    X                 K 

(5        D 

1   «s 

-0  i 

w   « 

S>l 

*O           O\      O    N    rOOO    8    O\VO       10         10      »0  10  T»-00  OO    O\>O    O  OO    >O  •*• 

s 

dl 

3  - 

III 

vg       vg      S-ln&cg  5-^8      2        o>^5-S1SSSSS,^^M1 

3  s 

HC£ 

>  & 

»—  .     ^ 

ae 
M 

%   f 

. 

•       '         I2"2    >>          >,          )H'                                                     2*    C 

It 

PH     w 

1 

c3 

-2    "§  *§  •  2  I  *S  >.  >."5  -S:5'2>»           S"-'S>»«w 

fc 

C/2 

^>    %%>    >    *                        55^ 

P 

c 

. 

•O       T3 

w 

SI 

3.3.^                                                                                   d        n' 

caccrt>.-.--»»     »       -     SS5S:S*3«8«S 

w 

-1 

"S  »H  ^  2  r^                                             p^    r*\ 

1 

t>»       OO*       O\  O    M    N    •*•  1O\O       t^       OO       O\  M    04    C^)  4"  lOVO  OO    O\  O    M 
H          H       H  X.lt,M   «l   M    (1       «          «      *                                                         MM 

o,  -   .»."»;»».   -     ~   «  o.  «  «  »  .  :  .  «  . 

c^     "                                             S05S 

124 


ANALYSES    OF   ARTESIAN    WATERS. 


puE  pBOjg 


pus 


PUB  m^ 


puB  qj6 


ui    . 

it   4) 


0 


nnt 

o 


1-'      C    O  VO  00   -*00 
rt     ^j    u">  ro  f<ivo  -4- 


o 


&  I 

5  ~ 


S      8 


jy     t« 
0 


•SUai 


ANALYSES    OF    WATER   SUPPLIED    TO    CITIES. 


125 


TABLE  SHOWING  THE  RELATIVE  PURITY  OF  THE  WATER  SUPPLIED 

TO  CITIES,  FROM  THE  DETERMINATIONS  MADE  IN 

JUNE,  1 88 1,  BY  A.  R.  LEEDS. 


.5 

4 

a 

£ 

g 

^ 

._• 

Parts  per  million. 

13 

TD 

0 

0 
>» 

d 

o 

o 

1 

3 

R 

f, 

0 

o 

M 

§ 

i 

£ 

pq 

A 

u 

Total  solids  

143.0 

118.0 

60.0 

93-° 

85.0 

115.0 

roo.o 

162  o 

"     hardness,  .    .    . 

44.0 

33-o 

22.7 

32.0 

21.0 

48.0 

55-o 

64.0 

Chlorine,  
Oxygen  -consuming 

3-5 

5-5 

2-35 

3-15 

2.70 

'•95 

8.05 

4.6 

8.1 

4.13 

9-5 

17.7 

6.  oo 

7  9 

8.6 

Nitrogen  by  KMnO4) 

•'4V 

.221 

.067 

•344 

.496 

.221 

.188 

.196 

Nitrogen  in  ammo- 

nium compounds.   . 
Nitrogen  as   nitrites. 

.008 
None. 

.022 

None. 

.006 
None. 

XT  '°39 
None. 

.108 

None. 

0.49 

None. 

XT'093 

None. 

.094 
None. 

"         "   nitrates. 

i.5« 

184 

2.69 

2.01 

2-75 

1.84 

1-39 

1.64 

INDEX. 


A  CIDS,  action  on  lead,  84 
•**•     Actinic  method  for  organic  matter, 

4i 

Action  of  water  on  lead,  83 
Aeration  of  water,  81 
Agar-Agar,  87 
Albuminoid  ammonia,  26,  72 
Alkali  carbonates,  determination  of,  61 
Alkaline  permanganate,  25 
Allen,  on  boiler  waters,  112 

,  lead  in  water,  84 

,  sulphuric  acid  in  water,  112 

,  test  for  zinc,  58 

Alum,  action  of,  102 

,  use  of,  102 

Aluminum,  determination  of,  53 

,  in  scale,  91 

Amido-naphthalene,  36 
Ammonia,  albuminoid,  26 

,  free,  25 

,  free  water,  25 

,  from  rain  water,  75 

process,  26 

Ammonium  chloride,  standard,  25 

molybdate,  42 

picrate  solution,  34 

Analysis,  statement  of,  70 

Analytical  operations,  16 

Anderson  and   Ogsten,   purification   of 

water,  103 
Animal  matter,  73 
Antwerp  water,  purification  of,  104 
Artesian  water,  9,  14 

waters,  composition  of,  124 

Arsenic,  detection  of,  48 
.effect  of,  73 


O  ACILLI,  species  of,  97 

•^^     Bacillus  typhosus,  culture  of,  96, 

9.7 

Bacteria  in  water,  85,  97 
Bacteriological  examination,  85 
Barium,  detection  and  estimation  of,  48 
Barren  Hill  well,  15,  122 
Barus,  Carl,  suspended  matters  in  water, 

ii 
Basin,  platinum,  19 


Bicarbpnates  in  water,  115 
Biological  examinations,  85 
Black's  Island  well,  73,  124 
Blarez'  oxygen  process,  44 
Boiler  mud,  113 
—  water,  111 

water,  points  to  be  determined  in, 

"3 

— — ,  purification  of,  114 

,  statement  of  results  from, 

114 

Boric  acid  estimation,  64 
Bottle  culture,  91 

for  test  solution,  23 

Burner,  low  temperature,  20 


PALCIUM  bicarbonate,  115 
^^    — — —  carbonate,  action  in  boiler 
waters,  113 

,  solubility  of,  115 

compounds,  removal  of,  115 

,  determination  of,  54 

hydroxide   for  purifying   water, 

"5 

sulphate,  insolubility  of,  113 

sulphate,  action  in  boiler  water, 

113 
Carbonates,  action  on  lead,  84 

,  determination  of  normal,  61 

Carbon  filters,  98 
Carbonic  acid,  action  of,  14 

,  free,  determination  of,  63 

,  effect  on  microbes,  93 

Carleton-Williams,  lead  in  water,  84 
Carnally  and  Frew,  lead  in  water,  84 
Caustic  soda,  use  of,  in  boiler  water,  115 
Cellar  waters,  examination  of,  109 
Chlorine,  determination  of,  22 

,  significance  of,  74 

Chromium,  detection  of,  48 

City  supplies,  125 

Clarifying  water,  17,  102 

Clark's  process  for  purifying  water,  115 

Color  comparators,  29 

,  determination  of,  18 

,  significance  of,  72 

Comparison  cylinders,  29 


127 


128 


INDEX. 


Control  determination,  21,  56 
Conversion  of  ratios,  119,  120 
Cooper,  A.  J.,  delicacy  of  tests,  53 
Copper,  detection  of,  52 

,  effects  of,  73 

sulphate,  standard,  52 

Corrosion  of  boilers,  in 

Crookes,  Odling  and  Tidy,  lead  in  water, 

83 

Cultivation  of  microbes,  86 
Culture  media,  86 


•T)EEP  water,  14,  74,  124 
*^     Demijohn  for  water  samples,  16 
Dibdin,  table  of  dissolved  oxygen,  121 
Distilled  water,  wholesomeness  of,  73 
Driffield,  composition  of  boiler  mud,  113 
Drown  and  Martin,  nitrogen  determina- 
tion, 31 
Dupre,  dissolved  oxygen,  47,  81 


"FERMENTATION,  butyric,  25 

•*•         Ferrous      ammonium      sulphate, 

standard, 44 

Ferric  sulphate,  standard,  50 
Filter  paper,  17 
Filters,  BischofTs,  99 

,  Pasteur-Chamberlain,  99 

, sand, xoo 


-,  spongy  iron,  99 
tion,  effect  of,  101 


Filtrati 

Fleck's  silver  method,  41 
Fluorescent,  use  of,  108 
Forceps,  platinum,  20 
Frankland,  purification  by  precipitation, 
102 

and  Tidy,  standards  of  purity,  80 

nitrifying  bacillus,  13 

ammonia,  25,  76 

Frew  and  Carnelly,  lead  in  water,  83 


GALLON,  Imperial,  70 
,  U.  S  ,  70 

Gelatin  culture  media.  86 

.  liquefaction  of,  92 

Gerardin,  dissolved  oxygen,  81 
Gooch,  method  for  borates,  64 
• ,  method  for  lithium,  59 


•LJ  ARDNESS,  determination  of,  62 

** ,  permanent,  62 

,  temporary,  62,  114 

Hard  scale,  113 

— — —  water,  sanitary  relations  of,  82 

—  water,  softening  of,  115 
Hehner.  limit  of  phosphates,  73 
Hehner  s  cylinders  for  color  compari- 
son, 39 


Hehner's  method  for  hardness,  62 

Heisch's  test,  43 

History  of  water,  9 

Hunt,  T.  Sterry,  water  in  rocks,  12 

Hyatt  filter,  103 

Hydrogen  sulphide,  titration  of,  60 

IDENTIFICATION    of    source     of 

•*•     water,  107 

Imperial  gallon,  70 

Interpretation  of  results,  70 

Indol  reaction,  94 

Iodine,  centinormal,  6p 

Iron,  action  of,  in  purification,  104 

—  compounds,  solution  by  water,  14 

,  determination  of,  50,  53 

,  significance  of,  73 


T^JELDAHL  method,  31 
•**•     Koch's  culture  method,  89 

T    ACMOID.useof,  19 

•*-'     Lead,  action  of  water  on,  83 

Lead,  determination  of,  51 

,  nitrate,  standard,  52 

,  significance  of,  73 

Leeds'  actinic  method,  41 

dissolved  oxygen,  81 

Lime,  purification  of  water  by,  98,  115 
Lithium  compounds,  use  of,  108 
,  detection  of,  67 

,  separation  of,  59 

Litmus,  use  of,  19 
Locust  Point  well,  15,  124 
Lott,  F.  E.,  Heisch's  test,  74 

TV/TAGNESIA  in  boiler  sludge,  114 
•*•'•*•      Magnesium,  determination  of,  55 
Magnesium     chloride,    decompositions 
and  effects  of,  114 

compounds,  removal  of,  115,  1 16 

Mallet,  ammonia  process,  76 
Manganese,  detection  of,  51 
— — — ,  determination  of,  55 
Microbes,  table  of,  97 
Mineral  springs,  14 
Mine  water,  112 
Miiller,  lead  in  water,  84 

TSJAPHTHYLAMINE,  36 

*^      National  filter,  103 

Nesslerizing,  29 

Nessler's  reagent,  25 

Nickel  dish,  20,62 

Nitric  acid,  diluted,  50 

Nitrification,  13 

Nitrates,  action  in  boilers,  112 


INDEX. 


I29 


Nitrates,  determination  of,  33 

,  formation  of,  13 

,  significance  of,  78 

Nitrites,  determination  of,  35 

,  formation  of,  13 

,  significance  of,  77 

Nitrogen  in  ammonium  compounds,  26, 

3^.74 

as  nitrites,  35 

as  nitrates,  33 

— —  by  permanganate,  75 

,  oxidation  of,  13 

,  total  organic,  30 


Ptomaines,  12 

Pure  water,  corrosive  action  of,  in 
Purification  of  boiler  water,  114 
of  drinking  waters,  98 

"DA  IN  water,  9,  80,  122 

*^     Ratios,  conversion  of,  119,  120 

Reaction,  19 

Residue,  charring  of.  21 

Results,  statement  of,  70 

River  water,  9,  10,  80,  123,  125 

Roll  culture,  91 


O 


DOR,  determination  of,  18 

from  residue,  21 

,  significance  of,  72 


Odling,    Crookes    and    Tidy,    lead    in 

water,  83 

Organic  matter,  12,  21,  71 
)f,  I 


,  action  of,  14 
,  oxidation  of,  40 


in  water,  86 
-,  precipitation  of,  102 


Oxygen  consumed,  37 

-consuming  microbes,  97 

-consuming  power,  37 

,  amount  of,  dissolved,  12 1 

,  dissolved,  determination  of,  44 
,  dissolved,  effects  of,  81,  in 


P ARA-AMIDO- BENZENE- SUL- 
PHONICacid,  36 
Pasteur-Chamberlain  filter,  83,  99 
Permanganate  method,  37 

standard,  37,  44 

Pettenkofer's  method  for  free  carbonic 

acid,  63 

Phenacetolin,  use  of,  62 
Phenolphthalein,  use  of,  19 
Phosphates,  action  on  lead,  84 

,  determination  of,  42 

,  significance  of,  73 

,  use  of,  in  purifying  water,  117 

Phenol-sulphonic  acid,  33 
Plate  culture,  89 
Platinum,  preservation  of,  20 
Plummet  for  specific  gravity,  68 
Poisonous  metals,  detection  of,  47 

,  significance  of,  69 

Polluted  waters,  characters  of,  67-77 
Porter's  process  for  purifying  water,  94 
Potassium  determination,  52 

chromate  solution,  22 

iodide  solution,  39 

nitrate,  standard,  33 

Potassium  permanganate,  alkaline,  25 

permanganate,  decinormal,  44 

Potato  culture,  88 
Preliminary  examination,  16 


O  ALT,  action  on  boiler  waters,  112 
^    Samples,  collection  of,  16 
Sand  filters,  ipo 
Sanitary  application,  71 

examinations,  16 

Scale,  112 

Schuylkill  River  water,  composition  of. 

10,  123 
Sewage,  action  of,  14,  80      % 

fungus,  43,  79 

Silica,  action  of,  in  water,  83 

,  determination  of,  53 

in  scale,  112 

Silicates,  action  on  lead,  84 
Silver  nitrate,  standard,  22 

,  test  in  Porter's  process, 

116 

nitrite,  preparation  of,  36 

test  for  organic  matter,  41 

Sludge,  113 

Solids,  total,  determination  of,  19 

Solids,  significance  of,  73 

Sodium  and  potassium,  separation  of,  58 

carbonate,  solution  of,  25 

,  standard,  62 

•  ,  use  of  in   boiler  waters, 

"5 

chloride,  standard,  23 

,  determination  of,  58 

hydroxide,  solution,  31 

nitrite,  standard,  36 

thiosulphate,  39 

Source  of  water,  tracing  of,  107 

Smart,  C.,  nature  of  organic  matter,  75 

Subsoil  waters,  composition  of,  12,  122 

Specific  gravity,  68 

Spectroscope,  67 

Spectroscopic  examination,  67 

Spongy  iron  filters,  99 

Staining,  93 

Starch  indicator,  39 

Sterilizer,  86 

Storage,  effect  of,  95 

Subsidence,  promotion  of,  17,  192 

Subsoil  water,  9,  n,  122 

Sugar  test,  42 

Sulphanilic  acid,  36 


1 3o 


INDEX. 


Sulphides,  formation  of,  14,  72 
Sulphuretted   hydrogen,   determination 

of,  14,  60 
Sulphuric  acid,  diluted,  31,  39 

,  standard,  62 

Surface  water,  composition  of,  9,  10, 123 
Suspended  matters,  10,  n 


np  AS  TE,  significance  of,  72 
•*•      Technical  examinations,  53 
Tests  for  metals,  delicacy  of,  53 
Thompson,  estimation  of  iron,  50 
Tidy's  permanganate  process,  38 
Tidy  and  Frankland,  standard  of  purity, 

79 

,  Odling  and    Crookes,  lead  in 

water,  83 

Tri-sodium  phosphate,  use  of,  for  puri- 
fication, 116 


TTNCONTAMINATED  waters,  82 
^     Urea,  decomposition  of,  75 
Urine  in  water,  75 
U.  S.  gallon,  70 


T7EGETABLE  matter,  21,  76 
"      Vegetable  growth  in  water,  81 


•\X7ARINGTON,  R.,  nitrification,  13 
"v      Water,  amount  of,  in  rocks,  12 
Wanklyn,  standards  of  purity,  77 
Wanklyn's  albuminoid  ammonia    pro- 
cess, 23 
test  for  manganese,  51 


7INC,  detection  of,  48 
"     ,  effect  of,  72 


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